diff --git a/Alignment/HIPAlignmentAlgorithm/test/testHIPAnalyzers.cc b/Alignment/HIPAlignmentAlgorithm/test/testHIPAnalyzers.cc
index bad25808c0333..75692c3569534 100644
--- a/Alignment/HIPAlignmentAlgorithm/test/testHIPAnalyzers.cc
+++ b/Alignment/HIPAlignmentAlgorithm/test/testHIPAnalyzers.cc
@@ -2,6 +2,7 @@
 #include "FWCore/Utilities/interface/Exception.h"
 #include "FWCore/ServiceRegistry/interface/Service.h"
 #include "CommonTools/UtilAlgos/interface/TFileService.h"
+#include <format>
 
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
@@ -61,8 +62,8 @@ process.add_(cms.Service('JobReportService'))
 process.add_(cms.Service('TFileService',fileName=cms.string('{}')))
     )_";
 
-  // Format the raw string literal using fmt::format
-  return fmt::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
+  // Format the raw string literal using std::format
+  return std::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
 }
 
 //___________________________________________________________________________________________
diff --git a/Alignment/OfflineValidation/test/testTrackAnalyzers.cc b/Alignment/OfflineValidation/test/testTrackAnalyzers.cc
index 8efeab347a878..fbef6338487b3 100644
--- a/Alignment/OfflineValidation/test/testTrackAnalyzers.cc
+++ b/Alignment/OfflineValidation/test/testTrackAnalyzers.cc
@@ -4,6 +4,7 @@
 #include "CommonTools/UtilAlgos/interface/TFileService.h"
 #include "Alignment/OfflineValidation/interface/TkAlStyle.h"
 
+#include <format>
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
 
@@ -56,8 +57,8 @@ process.add_(cms.Service('JobReportService'))
 process.add_(cms.Service('TFileService',fileName=cms.string('{}')))
     )_";
 
-  // Format the raw string literal using fmt::format
-  return fmt::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
+  // Format the raw string literal using std::format
+  return std::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
 }
 
 //___________________________________________________________________________________________
diff --git a/CalibTracker/SiPixelESProducers/test/test_catch2_ESSources.cc b/CalibTracker/SiPixelESProducers/test/test_catch2_ESSources.cc
index 3384cecc4f00f..f556d6261bd3f 100644
--- a/CalibTracker/SiPixelESProducers/test/test_catch2_ESSources.cc
+++ b/CalibTracker/SiPixelESProducers/test/test_catch2_ESSources.cc
@@ -1,6 +1,7 @@
 #include "FWCore/TestProcessor/interface/TestProcessor.h"
 #include "FWCore/Utilities/interface/Exception.h"
 #include "FWCore/ServiceRegistry/interface/Service.h"
+#include <format>
 
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
@@ -62,8 +63,8 @@ process.add_(cms.Service('JobReportService'))
 process.moduleToTest(process.getConditions)
     )_";
 
-  // Format the raw string literal using fmt::format
-  return fmt::format(rawString, recordName, dataName, esProducerName);
+  // Format the raw string literal using std::format
+  return std::format(rawString, recordName, dataName, esProducerName);
 }
 
 //___________________________________________________________________________________________
diff --git a/DQM/EcalCommon/test/testEcalCommon.cc b/DQM/EcalCommon/test/testEcalCommon.cc
index d4eb9db6a0875..73e566c869f47 100644
--- a/DQM/EcalCommon/test/testEcalCommon.cc
+++ b/DQM/EcalCommon/test/testEcalCommon.cc
@@ -1,6 +1,7 @@
 #include "FWCore/TestProcessor/interface/TestProcessor.h"
 #include "FWCore/Utilities/interface/Exception.h"
 #include "FWCore/ServiceRegistry/interface/Service.h"
+#include <format>
 
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
@@ -32,8 +33,8 @@ process.add_(cms.Service('JobReportService'))
 process.add_(cms.Service('DQMStore'))
     )_";
 
-  // Format the raw string literal using fmt::format
-  return fmt::format(rawString, cfiName, analyzerName, analyzerName);
+  // Format the raw string literal using std::format
+  return std::format(rawString, cfiName, analyzerName, analyzerName);
 }
 
 //___________________________________________________________________________________________
diff --git a/DQM/HcalTasks/plugins/HcalFEDIntegrityTask.cc b/DQM/HcalTasks/plugins/HcalFEDIntegrityTask.cc
index 6ef60e681abf3..87d6defd67e00 100644
--- a/DQM/HcalTasks/plugins/HcalFEDIntegrityTask.cc
+++ b/DQM/HcalTasks/plugins/HcalFEDIntegrityTask.cc
@@ -17,6 +17,7 @@
 
 #include <vector>
 #include <string>
+#include <format>
 
 using namespace std;
 using namespace edm;
@@ -141,7 +142,7 @@ void HcalFEDIntegrityTask::labelBins(MonitorElement *me) {
     return;
 
   for (int i = 0; i < xbins; i++) {
-    const std::string xLabel = fmt::format("{}", minFEDNum_ + i);
+    const std::string xLabel = std::format("{}", minFEDNum_ + i);
     me->setBinLabel(i + 1, xLabel, 1);
   }
 }
diff --git a/DQM/RPCMonitorClient/plugins/RPCEventSummary.cc b/DQM/RPCMonitorClient/plugins/RPCEventSummary.cc
index be357e2155b49..10f63cb4590bb 100644
--- a/DQM/RPCMonitorClient/plugins/RPCEventSummary.cc
+++ b/DQM/RPCMonitorClient/plugins/RPCEventSummary.cc
@@ -5,6 +5,7 @@
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 #include "FWCore/Framework/interface/EventSetup.h"
 #include "FWCore/Framework/interface/ESHandle.h"
+#include <format>
 
 RPCEventSummary::RPCEventSummary(const edm::ParameterSet& ps) {
   edm::LogVerbatim("rpceventsummary") << "[RPCEventSummary]: Constructor";
@@ -95,14 +96,14 @@ void RPCEventSummary::dqmEndLuminosityBlock(DQMStore::IBooker& ibooker,
 
     std::vector<std::string> segmentNames;
     for (int i = -2; i <= 2; i++) {
-      const std::string segName = fmt::format("RPC_Wheel{}", i);
+      const std::string segName = std::format("RPC_Wheel{}", i);
       segmentNames.push_back(segName);
     }
 
     for (int i = -numberDisk_; i <= numberDisk_; i++) {
       if (i == 0)
         continue;
-      const std::string segName = fmt::format("RPC_Disk{}", i);
+      const std::string segName = std::format("RPC_Disk{}", i);
       segmentNames.push_back(segName);
     }
 
@@ -146,8 +147,8 @@ void RPCEventSummary::clientOperation(DQMStore::IGetter& igetter) {
   float barrelFactor = 0;
 
   for (int w = -2; w < 3; w++) {
-    const std::string meName1 = fmt::format("{}/DeadChannelFraction_Roll_vs_Sector_Wheel{}", globalFolder_, w);
-    const std::string meName2 = fmt::format("{}/RPCNoisyStrips_Roll_vs_Sector_Wheel{}", globalFolder_, w);
+    const std::string meName1 = std::format("{}/DeadChannelFraction_Roll_vs_Sector_Wheel{}", globalFolder_, w);
+    const std::string meName2 = std::format("{}/RPCNoisyStrips_Roll_vs_Sector_Wheel{}", globalFolder_, w);
     MonitorElement* myMe1 = igetter.get(meName1);
     MonitorElement* myMe2 = igetter.get(meName2);
 
@@ -182,7 +183,7 @@ void RPCEventSummary::clientOperation(DQMStore::IGetter& igetter) {
 
       wheelFactor = wheelFactor / myMe1->getNbinsX();
 
-      const std::string globalMEName = fmt::format("{}/reportSummaryContents/RPC_Wheel{}", eventInfoPath_, w);
+      const std::string globalMEName = std::format("{}/reportSummaryContents/RPC_Wheel{}", eventInfoPath_, w);
       MonitorElement* globalMe = igetter.get(globalMEName);
       if (globalMe)
         globalMe->Fill(wheelFactor);
@@ -201,8 +202,8 @@ void RPCEventSummary::clientOperation(DQMStore::IGetter& igetter) {
       if (d == 0)
         continue;
 
-      const std::string meName1 = fmt::format("{}/DeadChannelFraction_Ring_vs_Segment_Disk{}", globalFolder_, d);
-      const std::string meName2 = fmt::format("{}/RPCNoisyStrips_Ring_vs_Segment_Disk{}", globalFolder_, d);
+      const std::string meName1 = std::format("{}/DeadChannelFraction_Ring_vs_Segment_Disk{}", globalFolder_, d);
+      const std::string meName2 = std::format("{}/RPCNoisyStrips_Ring_vs_Segment_Disk{}", globalFolder_, d);
       MonitorElement* myMe1 = igetter.get(meName1);
       MonitorElement* myMe2 = igetter.get(meName2);
 
@@ -245,7 +246,7 @@ void RPCEventSummary::clientOperation(DQMStore::IGetter& igetter) {
 
         diskFactor = diskFactor / 6;
 
-        const std::string globalMEName = fmt::format("{}/reportSummaryContents/RPC_Disk{}", eventInfoPath_, d);
+        const std::string globalMEName = std::format("{}/reportSummaryContents/RPC_Disk{}", eventInfoPath_, d);
         MonitorElement* globalMe = igetter.get(globalMEName);
         if (globalMe)
           globalMe->Fill(diskFactor);
diff --git a/DQM/RPCMonitorClient/src/RPCClusterSizeTest.cc b/DQM/RPCMonitorClient/src/RPCClusterSizeTest.cc
index bafb112e79131..a37c096b1a430 100644
--- a/DQM/RPCMonitorClient/src/RPCClusterSizeTest.cc
+++ b/DQM/RPCMonitorClient/src/RPCClusterSizeTest.cc
@@ -4,6 +4,7 @@
 
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 #include "Geometry/RPCGeometry/interface/RPCGeomServ.h"
+#include <format>
 
 RPCClusterSizeTest::RPCClusterSizeTest(const edm::ParameterSet& ps) {
   edm::LogVerbatim("rpceventsummary") << "[RPCClusterSizeTest]: Constructor";
@@ -55,7 +56,7 @@ void RPCClusterSizeTest::clientOperation() {
     //Barrel
     for (int wheel = -2; wheel <= 2; wheel++) {
       for (int sector = 1; sector <= 12; sector++) {
-        std::string tmpName = fmt::format("ClusterSize_Wheel_{}_Sector_{}", wheel, sector);
+        std::string tmpName = std::format("ClusterSize_Wheel_{}_Sector_{}", wheel, sector);
 
         if (tmpName == meName) {
           MEAN = MEANWheel[wheel + 2];
@@ -97,7 +98,7 @@ void RPCClusterSizeTest::clientOperation() {
       for (int disk = 1; disk <= numberOfDisks_; disk++) {
         for (int ring = 2; ring < numberOfRings_ + 2; ring++) {
           for (unsigned int ich = 0; ich < chNames.size(); ich++) {
-            std::string tmpName = fmt::format("ClusterSize_Disk_{}_Ring_{}_{}", (region * disk), ring, chNames[ich]);
+            std::string tmpName = std::format("ClusterSize_Disk_{}_Ring_{}_{}", (region * disk), ring, chNames[ich]);
 
             if (tmpName == meName) {
               xBin = (ich * 9);
diff --git a/DQM/RPCMonitorDigi/src/RPCFEDIntegrity.cc b/DQM/RPCMonitorDigi/src/RPCFEDIntegrity.cc
index 15cf5f478ab07..da13f1d2fdd71 100644
--- a/DQM/RPCMonitorDigi/src/RPCFEDIntegrity.cc
+++ b/DQM/RPCMonitorDigi/src/RPCFEDIntegrity.cc
@@ -4,6 +4,8 @@
 #include "DQM/RPCMonitorDigi/interface/RPCRawDataCountsHistoMaker.h"
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 
+#include <format>
+
 RPCFEDIntegrity::RPCFEDIntegrity(const edm::ParameterSet& ps) {
   edm::LogVerbatim("rpcfedintegrity") << "[RPCFEDIntegrity]: Constructor";
 
@@ -70,7 +72,7 @@ void RPCFEDIntegrity::labelBins(MonitorElement* myMe) {
     return;
 
   for (int i = 0; i < xbins; i++) {
-    const std::string xLabel = fmt::format("{}", minFEDNum_ + i);
+    const std::string xLabel = std::format("{}", minFEDNum_ + i);
     myMe->setBinLabel(i + 1, xLabel, 1);
   }
 }
diff --git a/DQM/TrackingMonitorSource/test/testTrackingDQMAnalyzers.cc b/DQM/TrackingMonitorSource/test/testTrackingDQMAnalyzers.cc
index c4c5248e559fe..7404a06c480ae 100644
--- a/DQM/TrackingMonitorSource/test/testTrackingDQMAnalyzers.cc
+++ b/DQM/TrackingMonitorSource/test/testTrackingDQMAnalyzers.cc
@@ -2,6 +2,7 @@
 #include "FWCore/Utilities/interface/Exception.h"
 #include "FWCore/ServiceRegistry/interface/Service.h"
 #include "CommonTools/UtilAlgos/interface/TFileService.h"
+#include <format>
 
 #define CATCH_CONFIG_MAIN
 #include "catch.hpp"
@@ -57,8 +58,8 @@ process.add_(cms.Service('JobReportService'))
 process.add_(cms.Service('TFileService',fileName=cms.string('{}')))
     )_";
 
-  // Format the raw string literal using fmt::format
-  return fmt::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
+  // Format the raw string literal using std::format
+  return std::format(rawString, analyzerName, analyzerName, analyzerName, rootFileName);
 }
 
 //___________________________________________________________________________________________
diff --git a/DQMServices/StreamerIO/test/BuildFile.xml b/DQMServices/StreamerIO/test/BuildFile.xml
index 51bfce9ce2b3b..ed32b59d9b143 100644
--- a/DQMServices/StreamerIO/test/BuildFile.xml
+++ b/DQMServices/StreamerIO/test/BuildFile.xml
@@ -3,6 +3,7 @@
 <use name="EventFilter/Utilities"/>
 <use name="DQMServices/Components"/>
 <use name="stdcxx-fs"/>
+<use name="fmt"/>
 <library file="*.cc" name="DQMServicesStreamerIOTestPlugins">
   <flags EDM_PLUGIN="1"/>
 </library>
diff --git a/DataFormats/CSCDigi/src/CSCWireDigi.cc b/DataFormats/CSCDigi/src/CSCWireDigi.cc
index ae5be38819c37..582723813f59c 100644
--- a/DataFormats/CSCDigi/src/CSCWireDigi.cc
+++ b/DataFormats/CSCDigi/src/CSCWireDigi.cc
@@ -7,6 +7,7 @@
 #include "DataFormats/CSCDigi/interface/CSCWireDigi.h"
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 #include <iostream>
+#include <iterator>
 #include <cstdint>
 
 /// Constructors
diff --git a/DataFormats/FEDRawData/interface/SLinkRocketHeaders.h b/DataFormats/FEDRawData/interface/SLinkRocketHeaders.h
index 457fc657f353e..8487d3fda19c6 100644
--- a/DataFormats/FEDRawData/interface/SLinkRocketHeaders.h
+++ b/DataFormats/FEDRawData/interface/SLinkRocketHeaders.h
@@ -3,7 +3,7 @@
 
 #include "FWCore/Utilities/interface/Exception.h"
 
-//#include <memory>
+#include <memory>
 #include <span>
 
 /*
diff --git a/DataFormats/FEDRawData/src/RawDataBuffer.cc b/DataFormats/FEDRawData/src/RawDataBuffer.cc
index ebbc6dd22e409..9910cd670fa17 100644
--- a/DataFormats/FEDRawData/src/RawDataBuffer.cc
+++ b/DataFormats/FEDRawData/src/RawDataBuffer.cc
@@ -7,6 +7,8 @@
 #include <DataFormats/FEDRawData/interface/RawDataBuffer.h>
 #include <DataFormats/FEDRawData/interface/FEDNumbering.h>
 #include <DataFormats/FEDRawData/interface/SourceIDNumbering.h>
+#include "FWCore/Utilities/interface/Exception.h"
+#include <cstring>
 
 RawDataBuffer::RawDataBuffer() {}
 RawDataBuffer::RawDataBuffer(uint32_t preallocSize) : usedSize_(0), data_(preallocSize) {}
diff --git a/DataFormats/Provenance/src/ThinnedAssociationsHelper.cc b/DataFormats/Provenance/src/ThinnedAssociationsHelper.cc
index 3c6131e2c0886..4c1472b48b9a8 100644
--- a/DataFormats/Provenance/src/ThinnedAssociationsHelper.cc
+++ b/DataFormats/Provenance/src/ThinnedAssociationsHelper.cc
@@ -3,7 +3,7 @@
 #include "FWCore/Utilities/interface/EDMException.h"
 #include <algorithm>
 
-#include <fmt/format.h>
+#include <format>
 
 namespace edm {
 
@@ -72,7 +72,7 @@ namespace edm {
         ensureSlimmingConstraints();
       } catch (edm::Exception& ex) {
         ex.addContext("Calling ThinnedAssociationsHelper::addAssociation()");
-        ex.addAdditionalInfo(fmt::format("When adding a slimmed collection with BranchID {}", branches.thinned().id()));
+        ex.addAdditionalInfo(std::format("When adding a slimmed collection with BranchID {}", branches.thinned().id()));
         throw ex;
       }
     }
diff --git a/DataFormats/SoATemplate/BuildFile.xml b/DataFormats/SoATemplate/BuildFile.xml
index 00e24da5047ac..ab3499e61e144 100644
--- a/DataFormats/SoATemplate/BuildFile.xml
+++ b/DataFormats/SoATemplate/BuildFile.xml
@@ -1,4 +1,3 @@
 <use name="boost_header"/>
-<use name="fmt"/>
 <use name="FWCore/Reflection" source_only="1"/>
 <use name="FWCore/Utilities" source_only="1"/>
diff --git a/DataFormats/SoATemplate/interface/SoACommon.h b/DataFormats/SoATemplate/interface/SoACommon.h
index 79c605a63e874..49ee141c88803 100644
--- a/DataFormats/SoATemplate/interface/SoACommon.h
+++ b/DataFormats/SoATemplate/interface/SoACommon.h
@@ -17,7 +17,7 @@
 
 #include <boost/preprocessor.hpp>
 
-#include <fmt/format.h>
+#include <format>
 
 #include "FWCore/Utilities/interface/typedefs.h"
 
@@ -49,7 +49,7 @@
   }
 #else
 #define SOA_THROW_OUT_OF_RANGE(A, I, R) \
-  { throw std::out_of_range(fmt::format("{}: index {} out of range {}", (A), (I), (R))); }
+  { throw std::out_of_range(std::format("{}: index {} out of range {}", (A), (I), (R))); }
 #endif
 
 /* declare "scalars" (one value shared across the whole SoA) and "columns" (one value per element) */
diff --git a/EventFilter/CTPPSRawToDigi/plugins/TotemVFATRawToDigi.cc b/EventFilter/CTPPSRawToDigi/plugins/TotemVFATRawToDigi.cc
index f16c4c1b1d0c3..daad30cab1415 100644
--- a/EventFilter/CTPPSRawToDigi/plugins/TotemVFATRawToDigi.cc
+++ b/EventFilter/CTPPSRawToDigi/plugins/TotemVFATRawToDigi.cc
@@ -41,6 +41,7 @@
 #include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
 
 #include <string>
+#include <format>
 
 class TotemVFATRawToDigi : public edm::stream::EDProducer<> {
 public:
@@ -209,7 +210,7 @@ void TotemVFATRawToDigi::run(edm::Event &event, const edm::EventSetup &es) {
     if (analysisMaskHandle.isValid() && !analysisMaskHandle.failedToGet()) {
       analysisMask = *analysisMaskHandle;
     } else {
-      errSummary.add(fmt::format("No AnalysisMask found for {0}", subSystemName), "");
+      errSummary.add(std::format("No AnalysisMask found for {0}", subSystemName), "");
       analysisMask = TotemAnalysisMask();
     }
 
diff --git a/EventFilter/CTPPSRawToDigi/src/CTPPSPixelDataFormatter.cc b/EventFilter/CTPPSRawToDigi/src/CTPPSPixelDataFormatter.cc
index 120a66988305b..806ca0e891e84 100644
--- a/EventFilter/CTPPSRawToDigi/src/CTPPSPixelDataFormatter.cc
+++ b/EventFilter/CTPPSRawToDigi/src/CTPPSPixelDataFormatter.cc
@@ -12,6 +12,7 @@
 #include <bitset>
 #include <sstream>
 #include <iostream>
+#include <format>
 
 using namespace edm;
 using namespace std;
@@ -176,7 +177,7 @@ void CTPPSPixelDataFormatter::interpretRawData(
         } else if ((nroc - 1) >= maxRocIndex) {
           m_ErrorCheck.conversionError(fedId, iD, InvalidROCId, ww, errors);
           m_ErrorSummary.add("Invalid ROC",
-                             fmt::format("Id {0}, in link {1}, of FED {2} in DetId {3}", convroc, nlink, fedId, iD));
+                             std::format("Id {0}, in link {1}, of FED {2} in DetId {3}", convroc, nlink, fedId, iD));
 
         } else {
           m_ErrorCheck.conversionError(fedId, iD, Unknown, ww, errors);
@@ -210,7 +211,7 @@ void CTPPSPixelDataFormatter::interpretRawData(
     if (!isRun3 && (dcol < min_Dcol || dcol > max_Dcol || pxid < min_Pixid || pxid > max_Pixid)) {
       m_ErrorSummary.add(
           "unphysical dcol and/or pxid",
-          fmt::format("fedId= {0}, nllink= {1}, convroc= {2}, adc= {3}, dcol= {4}, pxid= {5}, detId= {6}",
+          std::format("fedId= {0}, nllink= {1}, convroc= {2}, adc= {3}, dcol= {4}, pxid= {5}, detId= {6}",
                       fedId,
                       nlink,
                       convroc,
@@ -225,7 +226,7 @@ void CTPPSPixelDataFormatter::interpretRawData(
     }
     if (isRun3 && (col < min_COL || col > max_COL || row < min_ROW || row > max_ROW)) {
       m_ErrorSummary.add("unphysical col and/or row",
-                         fmt::format("fedId= {0}, nllink= {1}, convroc= {2}, adc= {3}, col= {4}, row= {5}, detId= {6}",
+                         std::format("fedId= {0}, nllink= {1}, convroc= {2}, adc= {3}, col= {4}, row= {5}, detId= {6}",
                                      fedId,
                                      nlink,
                                      convroc,
diff --git a/EventFilter/SiStripRawToDigi/plugins/SiStripDigiToRaw.cc b/EventFilter/SiStripRawToDigi/plugins/SiStripDigiToRaw.cc
index e2c179cb33551..774e0410cd698 100644
--- a/EventFilter/SiStripRawToDigi/plugins/SiStripDigiToRaw.cc
+++ b/EventFilter/SiStripRawToDigi/plugins/SiStripDigiToRaw.cc
@@ -1,8 +1,7 @@
 #include <iomanip>
 #include <iostream>
 #include <sstream>
-
-#include <fmt/format.h>
+#include <format>
 
 #include "CondFormats/SiStripObjects/interface/SiStripFedCabling.h"
 #include "DataFormats/FEDRawData/interface/FEDHeader.h"
@@ -136,7 +135,7 @@ namespace sistrip {
 
           //need to construct full object to copy full header
           if (rawfedData.size() == 0)
-            warnings_.add("Invalid raw data for FED, skipping", fmt::format("id {0}", *ifed));
+            warnings_.add("Invalid raw data for FED, skipping", std::format("id {0}", *ifed));
           const auto st_buffer = preconstructCheckFEDBuffer(rawfedData, true);
           if (FEDBufferStatusCode::SUCCESS != st_buffer) {
             edm::LogWarning("DigiToRaw") << "[sistrip::DigiToRaw::createFedBuffers_]"
@@ -150,7 +149,7 @@ namespace sistrip {
                                          << " Could not construct FEDBuffer for FED " << *ifed << std::endl;
           }
           if (fedbuffer.headerType() == sistrip::HEADER_TYPE_INVALID) {
-            warnings_.add("Invalid header type for FED, skipping", fmt::format("id {0}", *ifed));
+            warnings_.add("Invalid header type for FED, skipping", std::format("id {0}", *ifed));
             continue;
           }
 
diff --git a/EventFilter/SiStripRawToDigi/plugins/SiStripRawToDigiUnpacker.cc b/EventFilter/SiStripRawToDigi/plugins/SiStripRawToDigiUnpacker.cc
index e914d689d699d..7b887b20b5e12 100644
--- a/EventFilter/SiStripRawToDigi/plugins/SiStripRawToDigiUnpacker.cc
+++ b/EventFilter/SiStripRawToDigi/plugins/SiStripRawToDigiUnpacker.cc
@@ -3,7 +3,7 @@
 #include <iomanip>
 #include <ext/algorithm>
 
-#include <fmt/format.h>
+#include <format>
 
 #include "CondFormats/SiStripObjects/interface/SiStripFedCabling.h"
 #include "DataFormats/Common/interface/DetSet.h"
@@ -155,12 +155,12 @@ namespace sistrip {
       // construct FEDBuffer
       if (FEDBufferStatusCode::SUCCESS != st_buffer) {
         if (FEDBufferStatusCode::BUFFER_NULL == st_buffer) {
-          warnings_.add("NULL pointer to FEDRawData for FED", fmt::format("id {0}", *ifed));
+          warnings_.add("NULL pointer to FEDRawData for FED", std::format("id {0}", *ifed));
         } else if (!input.size()) {
-          warnings_.add("FEDRawData has zero size for FED", fmt::format("id {0}", *ifed));
+          warnings_.add("FEDRawData has zero size for FED", std::format("id {0}", *ifed));
         } else {
           warnings_.add("Exception caught when creating FEDBuffer object for FED",
-                        fmt::format("id {0}: {1}", *ifed, static_cast<int>(st_buffer)));
+                        std::format("id {0}: {1}", *ifed, static_cast<int>(st_buffer)));
         }
         // FED buffer is bad and should not be unpacked. Skip this FED and mark all modules as bad.
         maskFED(detids, conns);
@@ -170,20 +170,20 @@ namespace sistrip {
       const FEDBufferStatusCode st_chan = buffer.findChannels();
       if (FEDBufferStatusCode::SUCCESS != st_chan) {
         warnings_.add("Exception caught when creating FEDBuffer object for FED",
-                      fmt::format("id {0}: {1}", *ifed, static_cast<int>(st_chan)));
+                      std::format("id {0}: {1}", *ifed, static_cast<int>(st_chan)));
         maskFED(detids, conns);
         continue;
       }
       buffer.setLegacyMode(legacy_);
       if ((!buffer.doChecks(true)) && (!unpackBadChannels_ || !buffer.checkNoFEOverflows())) {
         warnings_.add("Exception caught when creating FEDBuffer object for FED",
-                      fmt::format("id {0}: FED Buffer check fails for FED ID {0}.", *ifed));
+                      std::format("id {0}: FED Buffer check fails for FED ID {0}.", *ifed));
         maskFED(detids, conns);
         continue;
       }
       if (doFullCorruptBufferChecks_ && !buffer.doCorruptBufferChecks()) {
         warnings_.add("Exception caught when creating FEDBuffer object for FED",
-                      fmt::format("id {0}: FED corrupt buffer check fails for FED ID {0}.", *ifed));
+                      std::format("id {0}: FED corrupt buffer check fails for FED ID {0}.", *ifed));
         maskFED(detids, conns);
         continue;
       }
@@ -295,11 +295,11 @@ namespace sistrip {
               fedChannel, std::back_inserter(zs_work_digis_), ipair * 256, isNonLite, mode, legacy_, lmode, pCode);
           if (fedchannelunpacker::StatusCode::ZERO_PACKET_CODE == st_ch ||
               fedchannelunpacker::StatusCode::BAD_PACKET_CODE == st_ch) {
-            warnings_.add(fmt::format("Invalid packet code {0:#x} for zero-suppressed data", uint16_t(pCode)),
-                          fmt::format("FED {0} channel {1}", *ifed, iconn->fedCh()));
+            warnings_.add(std::format("Invalid packet code {0:#x} for zero-suppressed data", uint16_t(pCode)),
+                          std::format("FED {0} channel {1}", *ifed, iconn->fedCh()));
           } else if (fedchannelunpacker::StatusCode::SUCCESS != st_ch) {
             warnings_.add("Clusters are not ordered",
-                          fmt::format("FED {0} channel {1}: {2}", *ifed, iconn->fedCh(), toString(st_ch)));
+                          std::format("FED {0} channel {1}: {2}", *ifed, iconn->fedCh(), toString(st_ch)));
             detids.push_back(iconn->detId());  //@@ Possible multiple entries (ok for Giovanni)
             continue;
           }
@@ -319,7 +319,7 @@ namespace sistrip {
             } else {
               detids.push_back(iconn->detId());  //@@ Possible multiple entries (ok for Giovanni)
               warnings_.add("Problem extracting common modes",
-                            fmt::format("FED {0} channel {1}:\n Request for CM median from channel with non-ZS "
+                            std::format("FED {0} channel {1}:\n Request for CM median from channel with non-ZS "
                                         "packet code. Packet code is {2}.",
                                         *ifed,
                                         iconn->fedCh(),
@@ -354,7 +354,7 @@ namespace sistrip {
               scope_work_registry_.push_back(regItem);
             }
           } else {  // Unknown readout mode! => assume scope mode
-            warnings_.add(fmt::format("Unknown FED readout mode ({0})! Assuming SCOPE MODE...", int(mode)));
+            warnings_.add(std::format("Unknown FED readout mode ({0})! Assuming SCOPE MODE...", int(mode)));
             Registry regItem(key, 0, scope_work_digis_.size(), 0);
             st_ch = fedchannelunpacker::unpackScope(fedChannel, std::back_inserter(scope_work_digis_));
             if (regItem.index != scope_work_digis_.size()) {
@@ -372,7 +372,7 @@ namespace sistrip {
             }
           }
           if (fedchannelunpacker::StatusCode::SUCCESS != st_ch) {
-            warnings_.add(toString(st_ch), fmt::format("FED {0} channel {1}:", *ifed, iconn->fedCh()));
+            warnings_.add(toString(st_ch), std::format("FED {0} channel {1}:", *ifed, iconn->fedCh()));
           }
         }
       }  // channel loop
diff --git a/EventFilter/Utilities/BuildFile.xml b/EventFilter/Utilities/BuildFile.xml
index 2270817d5ce0a..24768cea83453 100644
--- a/EventFilter/Utilities/BuildFile.xml
+++ b/EventFilter/Utilities/BuildFile.xml
@@ -1,6 +1,7 @@
 <use name="curl"/>
 <use name="stdcxx-fs"/>
 <use name="tbb"/>
+<use name="fmt"/>
 <use name="DataFormats/FEDRawData"/>
 <use name="DataFormats/L1ScoutingRawData"/>
 <use name="DataFormats/TCDS"/>
diff --git a/EventFilter/Utilities/src/DAQSourceModelsDTH.cc b/EventFilter/Utilities/src/DAQSourceModelsDTH.cc
index d9c93cedf54a4..3d920b7dc0535 100644
--- a/EventFilter/Utilities/src/DAQSourceModelsDTH.cc
+++ b/EventFilter/Utilities/src/DAQSourceModelsDTH.cc
@@ -9,6 +9,7 @@
 #include <unistd.h>
 #include <vector>
 #include <bitset>
+#include <format>
 
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 
@@ -252,7 +253,7 @@ void DataModeDTH::makeDataBlockView(unsigned char* addr, RawInputFile* rawFile)
           checksumValid_ = false;
           if (!checksumError_.empty())
             checksumError_ += "\n";
-          checksumError_ += fmt::format(
+          checksumError_ += std::format(
               "Found a wrong crc32c checksum in orbit header v{} run: {} orbit: {} sourceId: {} wcount: {} events: {} "
               "flags: {}. Expected {:x} but calculated {:x}",
               orbitHeader->version(),
diff --git a/FWCore/Framework/interface/ComponentMaker.h b/FWCore/Framework/interface/ComponentMaker.h
index 06557e8916b7f..7f15ef6b5fc8b 100644
--- a/FWCore/Framework/interface/ComponentMaker.h
+++ b/FWCore/Framework/interface/ComponentMaker.h
@@ -22,7 +22,7 @@
 #include <memory>
 #include <string>
 
-#include <fmt/format.h>
+#include <format>
 
 // user include files
 #include "FWCore/Framework/interface/ComponentDescription.h"
@@ -97,7 +97,7 @@ namespace edm {
             iConfiguration.registerIt();
           });
         } catch (cms::Exception& iException) {
-          iException.addContext(fmt::format(
+          iException.addContext(std::format(
               "Validating configuration of {} of type {} with label: '{}'", T::baseType(), modtype, moduleLabel));
           throw;
         }
diff --git a/FWCore/Framework/src/ESSourceProductResolverBase.cc b/FWCore/Framework/src/ESSourceProductResolverBase.cc
index 4840ea4f88b2c..cedaeb90e924e 100644
--- a/FWCore/Framework/src/ESSourceProductResolverBase.cc
+++ b/FWCore/Framework/src/ESSourceProductResolverBase.cc
@@ -11,7 +11,7 @@
 //
 
 // system include files
-#include <fmt/format.h>
+#include <format>
 
 // user include files
 #include "FWCore/Framework/interface/ESSourceProductResolverBase.h"
@@ -51,7 +51,7 @@ void edm::eventsetup::ESSourceProductResolverBase::doPrefetchAndSignals(
   try {
     convertException::wrap([&] { prefetch(iKey, EventSetupRecordDetails(&iRecord)); });
   } catch (cms::Exception& iException) {
-    iException.addContext(fmt::format(
+    iException.addContext(std::format(
         "Retrieving data product {} '{}' in record {}", iKey.type().name(), iKey.name().value(), iRecord.key().name()));
     exceptionContext(iException, context);
     throw;
diff --git a/FWCore/Framework/src/StreamSchedule.cc b/FWCore/Framework/src/StreamSchedule.cc
index 6a63804d9a76d..9fc1ee8cf4a49 100644
--- a/FWCore/Framework/src/StreamSchedule.cc
+++ b/FWCore/Framework/src/StreamSchedule.cc
@@ -38,7 +38,7 @@
 #include <limits>
 #include <list>
 #include <map>
-#include <fmt/format.h>
+#include <format>
 
 namespace edm {
 
@@ -248,7 +248,7 @@ namespace edm {
       if (not consumes.empty()) {
         bool foundAtLeastOneMatchingBranch = false;
         for (auto const& product : consumes) {
-          std::string branch = fmt::format("{}_{}_{}_{}",
+          std::string branch = std::format("{}_{}_{}_{}",
                                            product.type().friendlyClassName(),
                                            product.label().data(),
                                            product.instance().data(),
diff --git a/FWCore/Integration/test/BuildFile.xml b/FWCore/Integration/test/BuildFile.xml
index f5569f8c0b002..db95dfadd88f2 100644
--- a/FWCore/Integration/test/BuildFile.xml
+++ b/FWCore/Integration/test/BuildFile.xml
@@ -46,7 +46,6 @@
     <use name="FWCore/TestProcessor"/>
     <use name="DataFormats/Provenance"/>
     <use name="catch2"/>
-    <use name="fmt"/>
   </bin>
 
   <bin file="EDAlias_t.cpp">
@@ -55,7 +54,6 @@
     <use name="FWCore/TestProcessor"/>
     <use name="DataFormats/Provenance"/>
     <use name="catch2"/>
-    <use name="fmt"/>
   </bin>
 
   <test name="testFWCoreIntegrationTransform" command="cmsRun ${LOCALTOP}/src/FWCore/Integration/test/transformTest_cfg.py"/>
diff --git a/FWCore/Integration/test/EDAlias_t.cpp b/FWCore/Integration/test/EDAlias_t.cpp
index 4141f12ce10a5..d7063c7bf065a 100644
--- a/FWCore/Integration/test/EDAlias_t.cpp
+++ b/FWCore/Integration/test/EDAlias_t.cpp
@@ -6,7 +6,7 @@
 #include "FWCore/TestProcessor/interface/TestProcessor.h"
 
 #include <iostream>
-#include <fmt/format.h>
+#include <format>
 
 static constexpr auto s_tag = "[EDAlias]";
 
@@ -198,7 +198,7 @@ process.test = cms.EDProducer('AddIntsProducer',
 process.moduleToTest(process.test, cms.Task(process.intprod))
 )_"};
 
-  edm::test::TestProcessor::Config config{fmt::format(baseConfig, "'intalias:another'")};
+  edm::test::TestProcessor::Config config{std::format(baseConfig, "'intalias:another'")};
 
   SECTION("Base configuration is OK") { REQUIRE_NOTHROW(edm::test::TestProcessor(config)); }
 
@@ -230,12 +230,12 @@ process.moduleToTest(process.test, cms.Task(process.intprod))
 
   SECTION("Other product instances are not aliased") {
     {
-      edm::test::TestProcessor::Config config{fmt::format(baseConfig, "'intalias:foo'")};
+      edm::test::TestProcessor::Config config{std::format(baseConfig, "'intalias:foo'")};
       edm::test::TestProcessor tester(config);
       REQUIRE_THROWS_WITH(tester.test(), Catch::Contains("ProductNotFound"));
     }
     {
-      edm::test::TestProcessor::Config config{fmt::format(baseConfig, "'intalias'")};
+      edm::test::TestProcessor::Config config{std::format(baseConfig, "'intalias'")};
       edm::test::TestProcessor tester(config);
       REQUIRE_THROWS_WITH(tester.test(), Catch::Contains("ProductNotFound"));
     }
@@ -337,7 +337,7 @@ process.moduleToTest(process.test, cms.Task(process.intprod))
 )_"};
 
   SECTION("Type wildcard") {
-    edm::test::TestProcessor::Config config{fmt::format(
+    edm::test::TestProcessor::Config config{std::format(
         baseConfig,
         "intprod = cms.VPSet(cms.PSet(type = cms.string('*'), fromProductInstance = cms.string('nonexistent')))")};
 
@@ -348,7 +348,7 @@ process.moduleToTest(process.test, cms.Task(process.intprod))
 
   SECTION("Instance wildcard") {
     edm::test::TestProcessor::Config config{
-        fmt::format(baseConfig, "intprod = cms.VPSet(cms.PSet(type = cms.string('nonexistentType')))")};
+        std::format(baseConfig, "intprod = cms.VPSet(cms.PSet(type = cms.string('nonexistentType')))")};
 
     REQUIRE_THROWS_WITH(edm::test::TestProcessor(config),
                         Catch::Contains("There are no products of type 'nonexistentType'") &&
diff --git a/FWCore/Integration/test/ProcessAccelerator_t.cpp b/FWCore/Integration/test/ProcessAccelerator_t.cpp
index 58ae58041855f..e55a390321f74 100644
--- a/FWCore/Integration/test/ProcessAccelerator_t.cpp
+++ b/FWCore/Integration/test/ProcessAccelerator_t.cpp
@@ -6,7 +6,7 @@
 #include "FWCore/ParameterSetReader/interface/ParameterSetReader.h"
 #include "FWCore/TestProcessor/interface/TestProcessor.h"
 
-#include <fmt/format.h>
+#include <format>
 
 #include <iostream>
 #include <string_view>
@@ -17,8 +17,8 @@ namespace {
   std::string makeResolverConfig(bool enableOther, std::string_view accelerator, std::string_view variant) {
     const std::string appendOther = enableOther ? "self._enabled.append('other')" : "";
     const std::string explicitVariant =
-        variant.empty() ? std::string(variant) : fmt::format(", variant=cms.untracked.string('{}')", variant);
-    return fmt::format(
+        variant.empty() ? std::string(variant) : std::format(", variant=cms.untracked.string('{}')", variant);
+    return std::format(
         R"_(from FWCore.TestProcessor.TestProcess import *
 import FWCore.ParameterSet.Config as cms
 
diff --git a/FWCore/MessageLogger/BuildFile.xml b/FWCore/MessageLogger/BuildFile.xml
index 2b719a173e8e4..791d9d487d11d 100644
--- a/FWCore/MessageLogger/BuildFile.xml
+++ b/FWCore/MessageLogger/BuildFile.xml
@@ -1,7 +1,6 @@
 <use name="FWCore/Utilities"/>
 <use name="DataFormats/Provenance"/>
 <use name="boost"/>
-<use name="fmt"/>
 <use name="tinyxml2"/>
 <use name="tbb"/>
 <export>
diff --git a/FWCore/MessageLogger/interface/ErrorObj.h b/FWCore/MessageLogger/interface/ErrorObj.h
index 8afe69b190d0f..21bb13338bf1a 100644
--- a/FWCore/MessageLogger/interface/ErrorObj.h
+++ b/FWCore/MessageLogger/interface/ErrorObj.h
@@ -25,7 +25,7 @@
 #include "FWCore/MessageLogger/interface/ELextendedID.h"
 #include "FWCore/MessageLogger/interface/ELseverityLevel.h"
 
-#include "fmt/format.h"
+#include <format>
 
 #include <sstream>
 #include <string>
@@ -80,8 +80,8 @@ namespace edm {
     inline ErrorObj& operator<<(std::ostream& (*f)(std::ostream&));
     inline ErrorObj& operator<<(std::ios_base& (*f)(std::ios_base&));
     template <typename... Args>
-    inline ErrorObj& format(fmt::format_string<Args...> format, Args&&... args);
-    inline ErrorObj& vformat(std::string_view fmt, fmt::format_args args);
+    inline ErrorObj& format(std::format_string<Args...> format, Args&&... args);
+    inline ErrorObj& vformat(std::string_view fmt, std::format_args args);
 
     virtual ErrorObj& emitToken(std::string_view txt);
 
diff --git a/FWCore/MessageLogger/interface/ErrorObj.icc b/FWCore/MessageLogger/interface/ErrorObj.icc
index c0a8ed2d9e776..8ef4ff4eeeece 100644
--- a/FWCore/MessageLogger/interface/ErrorObj.icc
+++ b/FWCore/MessageLogger/interface/ErrorObj.icc
@@ -14,8 +14,6 @@
 
 #include <sstream>
 
-#include "fmt/ostream.h"
-
 namespace edm {
 
   // ----------------------------------------------------------------------
@@ -57,15 +55,15 @@ namespace edm {
   }
 
   template <typename... Args>
-  inline ErrorObj& ErrorObj::format(fmt::format_string<Args...> format, Args&&... args) {
-    auto str = fmt::format(std::move(format), std::forward<Args>(args)...);
+  inline ErrorObj& ErrorObj::format(std::format_string<Args...> format, Args&&... args) {
+    auto str = std::format(std::move(format), std::forward<Args>(args)...);
     if (!str.empty())
       emitToken(str);
     return *this;
   }
 
-  inline ErrorObj& ErrorObj::vformat(std::string_view format, fmt::format_args args) {
-    auto str = fmt::vformat(format, args);
+  inline ErrorObj& ErrorObj::vformat(std::string_view format, std::format_args args) {
+    auto str = std::vformat(format, args);
     if (!str.empty())
       emitToken(str);
     return *this;
diff --git a/FWCore/MessageLogger/interface/MessageLogger.h b/FWCore/MessageLogger/interface/MessageLogger.h
index 6e41427960656..2506df2f08b20 100644
--- a/FWCore/MessageLogger/interface/MessageLogger.h
+++ b/FWCore/MessageLogger/interface/MessageLogger.h
@@ -95,13 +95,13 @@ namespace edm {
     }
 
     template <typename... Args>
-    ThisLog& format(fmt::format_string<Args...> format, Args&&... args) {
+    ThisLog& format(std::format_string<Args...> format, Args&&... args) {
       if (ap.valid())
         ap.format(std::move(format), std::forward<Args>(args)...);
       return *this;
     }
 
-    ThisLog& vformat(std::string_view fmt, fmt::format_args args) {
+    ThisLog& vformat(std::string_view fmt, std::format_args args) {
       if (ap.valid())
         ap.vformat(fmt, args);
       return *this;
@@ -204,11 +204,11 @@ namespace edm {
     Suppress_LogDebug_& operator<<(std::ios_base& (*)(std::ios_base&)) { return *this; }
 
     template <typename... Args>
-    Suppress_LogDebug_& format(fmt::format_string<Args...> format, Args&&... args) {
+    Suppress_LogDebug_& format(std::format_string<Args...> format, Args&&... args) {
       return *this;
     }
 
-    Suppress_LogDebug_& vformat(std::string_view fmt, fmt::format_args args) { return *this; }
+    Suppress_LogDebug_& vformat(std::string_view fmt, std::format_args args) { return *this; }
 
     template <typename F>
     Suppress_LogDebug_& log(F&& iF) {
diff --git a/FWCore/MessageLogger/interface/MessageSender.h b/FWCore/MessageLogger/interface/MessageSender.h
index 0920d5a1c7d2b..014ad4c49832c 100644
--- a/FWCore/MessageLogger/interface/MessageSender.h
+++ b/FWCore/MessageLogger/interface/MessageSender.h
@@ -38,14 +38,14 @@ namespace edm {
     }
 
     template <typename... Args>
-    MessageSender& format(fmt::format_string<Args...> format, Args&&... args) {
+    MessageSender& format(std::format_string<Args...> format, Args&&... args) {
       if (valid())
         errorobj_p->format(std::move(format), std::forward<Args>(args)...);
       return *this;
     }
 
     template <typename... Args>
-    MessageSender& vformat(std::string_view fmt, fmt::format_args args) {
+    MessageSender& vformat(std::string_view fmt, std::format_args args) {
       if (valid())
         errorobj_p->vformat(fmt, args);
       return *this;
diff --git a/FWCore/MessageService/test/BuildFile.xml b/FWCore/MessageService/test/BuildFile.xml
index 4ca743ab52cbc..24e979e156227 100644
--- a/FWCore/MessageService/test/BuildFile.xml
+++ b/FWCore/MessageService/test/BuildFile.xml
@@ -261,8 +261,3 @@
   <use name="FWCore/Framework"/>
   <use name="FWCore/MessageLogger"/>
 </bin>
-
-<bin file="fmt_test.cppunit.cpp">
-  <use name="fmt"/>
-  <use name="cppunit"/>
-</bin>
diff --git a/FWCore/MessageService/test/UnitTestClient_C.cc b/FWCore/MessageService/test/UnitTestClient_C.cc
index 36b18e2ab22f5..ef204d7217668 100644
--- a/FWCore/MessageService/test/UnitTestClient_C.cc
+++ b/FWCore/MessageService/test/UnitTestClient_C.cc
@@ -34,9 +34,9 @@ namespace edmtest {
         .format("Test of format fill and width: ")
         .format("The following should read ++abcdefg $$$12: {:+>9} {:$>5}", "abcdefg", 12);
     edm::LogWarning("cat_A").vformat(std::string("Test of format precision: Pi with precision 12 is {:.12g}"),
-                                     fmt::make_format_args(d));
+                                     std::make_format_args(d));
     edm::LogWarning("cat_A").vformat("Test of format spacing: The following should read a b cc: {} {:+>} {:>2}",
-                                     fmt::make_format_args("a", "b", "cc"));
+                                     std::make_format_args("a", "b", "cc"));
   }
 
 }  // namespace edmtest
diff --git a/FWCore/MessageService/test/fmt_test.cppunit.cpp b/FWCore/MessageService/test/fmt_test.cppunit.cpp
deleted file mode 100644
index f3cf79fd28fc3..0000000000000
--- a/FWCore/MessageService/test/fmt_test.cppunit.cpp
+++ /dev/null
@@ -1,66 +0,0 @@
-/*----------------------------------------------------------------------
-
-Test program for fmt external.
-
- ----------------------------------------------------------------------*/
-
-#include <fmt/format.h>
-#include <cppunit/extensions/HelperMacros.h>
-
-class test_fmt_external : public CppUnit::TestFixture {
-  CPPUNIT_TEST_SUITE(test_fmt_external);
-
-  CPPUNIT_TEST(test_fmt);
-
-  CPPUNIT_TEST_SUITE_END();
-
-public:
-  void setUp() {}
-  void tearDown() {}
-  void test_fmt();
-};
-
-///registration of the test so that the runner can find it
-CPPUNIT_TEST_SUITE_REGISTRATION(test_fmt_external);
-
-//using std::cerr;
-//using std::endl;
-
-struct date {
-  int year, month, day;
-};
-
-template <>
-struct fmt::formatter<date> {
-  constexpr auto parse(format_parse_context& ctx) { return ctx.begin(); }
-
-  template <typename FormatContext>
-  auto format(const date& d, FormatContext& ctx) {
-    return format_to(ctx.out(), "{}-{}-{}", d.year, d.month, d.day);
-  }
-};
-
-template <typename... Args>
-auto capture(const Args&... args) {
-  return std::make_tuple(args...);
-}
-
-auto vprint_message = [](auto&& format, auto&&... args) {
-  fmt::vprint(format, fmt::make_format_args(std::forward<decltype(args)>(args)...));
-};
-
-void test_fmt_external::test_fmt()
-
-{
-  std::string s = fmt::format("The date is {}", date{2012, 12, 9});
-  std::string s_check = "The date is 2012-12-9";
-  CPPUNIT_ASSERT(s_check == s);
-  auto args = capture("{} {}", 42, "foo");
-  std::apply(vprint_message, args);
-  auto buf = fmt::memory_buffer();
-  format_to(std::back_inserter(buf), "{}", 42);  // replaces itoa(42, buffer, 10)
-  fmt::vprint(to_string(buf), fmt::make_format_args());
-  format_to(std::back_inserter(buf), "{:x}", 42);  // replaces itoa(42, buffer, 16)
-  fmt::vprint(to_string(buf), fmt::make_format_args());
-}
-#include <Utilities/Testing/interface/CppUnit_testdriver.icpp>
diff --git a/FWCore/Services/plugins/CPU.cc b/FWCore/Services/plugins/CPU.cc
index 68a251e94b9b4..d800288f24c62 100644
--- a/FWCore/Services/plugins/CPU.cc
+++ b/FWCore/Services/plugins/CPU.cc
@@ -40,7 +40,7 @@
 #include <set>
 #include <utility>
 #include <vector>
-#include <fmt/format.h>
+#include <format>
 
 #ifdef __linux__
 #include <sched.h>
@@ -247,16 +247,16 @@ namespace edm {
       model = info.brand_string;
 #elif defined(CPU_FEATURES_ARCH_ARM)
       const auto info{GetArmInfo()};
-      model = fmt::format("ARM {} {} {}", info.implementer, info.architecture, info.variant);
+      model = std::format("ARM {} {} {}", info.implementer, info.architecture, info.variant);
 #elif defined(CPU_FEATURES_ARCH_AARCH64)
       const auto info{GetAarch64Info()};
-      model = fmt::format("aarch64 {} {}", info.implementer, info.variant);
+      model = std::format("aarch64 {} {}", info.implementer, info.variant);
 #elif defined(CPU_FEATURES_ARCH_PPC)
       const auto strings{GetPPCPlatformStrings()};
       model = strings.machine;
 #elif defined(CPU_FEATURES_ARCH_RISCV)
       const auto info{GetRiscvInfo()};
-      model = fmt::format("riscv64 {} {}", info.vendor, info.uarch);
+      model = std::format("riscv64 {} {}", info.vendor, info.uarch);
 #endif
       return model;
     }
diff --git a/FWCore/Utilities/BuildFile.xml b/FWCore/Utilities/BuildFile.xml
index 9e5a6c7c5dd2f..3a547776f479c 100644
--- a/FWCore/Utilities/BuildFile.xml
+++ b/FWCore/Utilities/BuildFile.xml
@@ -1,6 +1,5 @@
 <use name="boost"/>
 <use name="libuuid"/>
-<use name="fmt"/>
 <use name="tbb"/>
 <use name="md5"/>
 <use name="stdcxx-fs"/>
diff --git a/FWCore/Utilities/bin/BuildFile.xml b/FWCore/Utilities/bin/BuildFile.xml
index a7ce6ff3436ad..77203154bf748 100644
--- a/FWCore/Utilities/bin/BuildFile.xml
+++ b/FWCore/Utilities/bin/BuildFile.xml
@@ -3,6 +3,5 @@
 </bin>
 
 <bin name="cms_adler32" file="adler32.cc">
-  <use name="fmt"/>
   <use name="zlib"/>
 </bin>
diff --git a/FWCore/Utilities/bin/adler32.cc b/FWCore/Utilities/bin/adler32.cc
index b20d10ce9bea7..961651f381c99 100644
--- a/FWCore/Utilities/bin/adler32.cc
+++ b/FWCore/Utilities/bin/adler32.cc
@@ -15,12 +15,13 @@
 #include <cstdio>
 #include <cstdlib>
 #include <fcntl.h>
-#include <fmt/format.h>
+#include <format>
 #include <iostream>
 #include <libgen.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <zlib.h>
+#include <memory>
 #ifdef __APPLE__
 typedef off_t off64_t;
 #define O_LARGEFILE 0
@@ -54,7 +55,7 @@ int main(int argc, char* argv[]) {
       fileSize += readSize;
     }
 
-    std::cout << fmt::format("{:x} {} {}\n", adlerCksum, fileSize, argv[fileNum]);
+    std::cout << std::format("{:x} {} {}\n", adlerCksum, fileSize, argv[fileNum]);
   }
 
   return (0);
diff --git a/FWCore/Utilities/interface/Exception.h b/FWCore/Utilities/interface/Exception.h
index f9c3e9888675d..69d323db6e0a7 100644
--- a/FWCore/Utilities/interface/Exception.h
+++ b/FWCore/Utilities/interface/Exception.h
@@ -41,7 +41,7 @@
 #include <string_view>
 #include <concepts>
 
-#include <fmt/format.h>
+#include <format>
 
 #include "FWCore/Utilities/interface/thread_safety_macros.h"
 #include "FWCore/Utilities/interface/Likely.h"
@@ -123,8 +123,8 @@ namespace cms {
     friend E& operator<<(E&& e, std::ios_base& (*f)(std::ios_base&));
 
     template <typename... Args>
-    inline void format(fmt::format_string<Args...> format, Args&&... args);
-    inline void vformat(std::string_view fmt, fmt::format_args args);
+    inline void format(std::format_string<Args...> format, Args&&... args);
+    inline void vformat(std::string_view fmt, std::format_args args);
 
     // This function is deprecated and we are in the process of removing
     // all code that uses it from CMSSW.  It will then be deleted.
@@ -153,11 +153,11 @@ namespace cms {
   // -------- implementation ---------
 
   template <typename... Args>
-  inline void Exception::format(fmt::format_string<Args...> format, Args&&... args) {
-    ost_ << fmt::format(std::move(format), std::forward<Args>(args)...);
+  inline void Exception::format(std::format_string<Args...> format, Args&&... args) {
+    ost_ << std::format(std::move(format), std::forward<Args>(args)...);
   }
 
-  inline void Exception::vformat(std::string_view format, fmt::format_args args) { ost_ << fmt::vformat(format, args); }
+  inline void Exception::vformat(std::string_view format, std::format_args args) { ost_ << std::vformat(format, args); }
 
   template <typename E, typename T>
     requires std::derived_from<std::remove_reference_t<E>, Exception>
diff --git a/FWCore/Utilities/src/Digest.cc b/FWCore/Utilities/src/Digest.cc
index 08d5785f2cfc4..83664a6c60c69 100644
--- a/FWCore/Utilities/src/Digest.cc
+++ b/FWCore/Utilities/src/Digest.cc
@@ -1,5 +1,6 @@
 #include <iomanip>
 #include <sstream>
+#include <cstring>
 
 #include "FWCore/Utilities/interface/EDMException.h"
 #include "FWCore/Utilities/interface/Digest.h"
diff --git a/HeterogeneousCore/AlpakaCore/plugins/ModuleTypeResolverAlpaka.cc b/HeterogeneousCore/AlpakaCore/plugins/ModuleTypeResolverAlpaka.cc
index e343e7b77b6b5..3800b58f580a1 100644
--- a/HeterogeneousCore/AlpakaCore/plugins/ModuleTypeResolverAlpaka.cc
+++ b/HeterogeneousCore/AlpakaCore/plugins/ModuleTypeResolverAlpaka.cc
@@ -8,6 +8,7 @@
 #include <cstring>
 #include <string>
 #include <unordered_map>
+#include <format>
 
 class ModuleTypeResolverAlpaka : public edm::ModuleTypeResolverBase {
 public:
@@ -42,7 +43,7 @@ class ModuleTypeResolverMakerAlpaka : public edm::ModuleTypeResolverMaker {
     if (modulePSet.existsAs<edm::ParameterSet>("alpaka", false)) {
       auto const& backend =
           modulePSet.getUntrackedParameter<edm::ParameterSet>("alpaka").getUntrackedParameter<std::string>("backend");
-      prefix = fmt::format("alpaka_{}::", backend);
+      prefix = std::format("alpaka_{}::", backend);
 
       LogDebug("AlpakaModuleTypeResolver")
           .format("AlpakaModuleTypeResolver: module {} backend prefix {}",
diff --git a/HeterogeneousCore/CUDAServices/plugins/BuildFile.xml b/HeterogeneousCore/CUDAServices/plugins/BuildFile.xml
index 535438b400fcd..a352551b9bfa1 100644
--- a/HeterogeneousCore/CUDAServices/plugins/BuildFile.xml
+++ b/HeterogeneousCore/CUDAServices/plugins/BuildFile.xml
@@ -1,6 +1,7 @@
 <iftool name="cuda">
   <use name="cuda"/>
   <use name="tbb"/>
+  <use name="fmt"/>
   <use name="DataFormats/Common"/>
   <use name="DataFormats/Provenance"/>
   <use name="FWCore/AbstractServices"/>
diff --git a/HeterogeneousCore/SonicTriton/src/TritonService.cc b/HeterogeneousCore/SonicTriton/src/TritonService.cc
index d0d82bbaa9efc..c1c0b6c4a7754 100644
--- a/HeterogeneousCore/SonicTriton/src/TritonService.cc
+++ b/HeterogeneousCore/SonicTriton/src/TritonService.cc
@@ -24,6 +24,7 @@
 #include <utility>
 #include <tuple>
 #include <unistd.h>
+#include <format>
 
 namespace tc = triton::client;
 
@@ -385,7 +386,7 @@ void TritonService::postEndJob() {
     printFallbackServerLog<edm::LogError>();
     if (rv != 0) {
       std::string stopCat("FallbackFailed");
-      std::string stopMsg = fmt::format("TritonService: Stopping the fallback server failed with exit code {}", rv);
+      std::string stopMsg = std::format("TritonService: Stopping the fallback server failed with exit code {}", rv);
       //avoid throwing if the stack is already unwinding
       if (callFails_ > 0)
         edm::LogWarning(stopCat) << stopMsg;
diff --git a/IOPool/Common/bin/BuildFile.xml b/IOPool/Common/bin/BuildFile.xml
index d3e1983302bfc..51dbcb9ad5656 100644
--- a/IOPool/Common/bin/BuildFile.xml
+++ b/IOPool/Common/bin/BuildFile.xml
@@ -1,6 +1,5 @@
 <bin name="edmProvDump" file="EdmProvDump.cc,">
   <use name="boost_program_options"/>
-  <use name="fmt"/>
   <use name="rootcore"/>
   <use name="DataFormats/Common"/>
   <use name="DataFormats/Provenance"/>
diff --git a/IOPool/Common/bin/EdmProvDump.cc b/IOPool/Common/bin/EdmProvDump.cc
index 1eb81558b5a37..72dc54a2c266b 100644
--- a/IOPool/Common/bin/EdmProvDump.cc
+++ b/IOPool/Common/bin/EdmProvDump.cc
@@ -27,7 +27,7 @@
 
 #include "boost/program_options.hpp"
 
-#include <fmt/format.h>
+#include <format>
 
 #include <cassert>
 #include <iostream>
@@ -114,7 +114,7 @@ namespace {
 
   std::string formatHeader(std::string_view text) {
     constexpr std::string_view decoration = "---------";
-    return fmt::format("{}{}{}", decoration, text, decoration);
+    return std::format("{}{}{}", decoration, text, decoration);
   }
 }  // namespace
 
diff --git a/IOPool/Input/src/RootInputFileSequence.cc b/IOPool/Input/src/RootInputFileSequence.cc
index e80822eeecd86..22730e8fc013f 100644
--- a/IOPool/Input/src/RootInputFileSequence.cc
+++ b/IOPool/Input/src/RootInputFileSequence.cc
@@ -279,11 +279,11 @@ namespace edm {
             throw ex;
           } else {
             exInfo.push_back("Calling RootInputFileSequence::initTheFile(): fail to open the file with name " + (*it));
-            additionalMessage.push_back(fmt::format(
+            additionalMessage.push_back(std::format(
                 "Input file {} could not be opened, and fallback was attempted.\nAdditional information:", *it));
             char c = 'a';
             for (auto const& ai : e.additionalInfo()) {
-              additionalMessage.push_back(fmt::format("  [{}] {}", c, ai));
+              additionalMessage.push_back(std::format("  [{}] {}", c, ai));
               ++c;
             }
           }
diff --git a/L1Trigger/L1TGlobal/plugins/BuildFile.xml b/L1Trigger/L1TGlobal/plugins/BuildFile.xml
index 3aa197fe126dc..1ab8c0bbd4e08 100644
--- a/L1Trigger/L1TGlobal/plugins/BuildFile.xml
+++ b/L1Trigger/L1TGlobal/plugins/BuildFile.xml
@@ -10,6 +10,7 @@
 <use name="CondFormats/DataRecord"/>
 <use name="xerces-c"/>
 <use name="utm"/>
+<use name="fmt"/>
 <use name="L1Trigger/L1TGlobal"/>
 <use name="L1Trigger/L1TCommon"/>
 <library file="*.cc" name="L1TriggerL1TGlobalPlugins">
diff --git a/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc b/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
index 8a14d52395e6e..651b3b40edf13 100644
--- a/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
+++ b/RecoMTD/TrackExtender/plugins/TrackExtenderWithMTD.cc
@@ -1,4 +1,5 @@
 #include <sstream>
+#include <format>
 
 #include <CLHEP/Units/GlobalPhysicalConstants.h>
 
@@ -980,12 +981,12 @@ void TrackExtenderWithMTDT<TrackCollection>::produce(edm::Event& ev, const edm::
 
         LogTrace("TrackExtenderWithMTD") << "TrackExtenderWithMTD: tmtd " << tmtdMap << " +/- " << sigmatmtdMap
                                          << " t0 " << t0Map << " +/- " << sigmat0Map << " tof pi/K/p " << tofpiMap
-                                         << "+/-" << fmt::format("{:0.2g}", sigmatofpiMap) << " ("
-                                         << fmt::format("{:0.2g}", sigmatofpiMap / tofpiMap * 100) << "%) " << tofkMap
-                                         << "+/-" << fmt::format("{:0.2g}", sigmatofkMap) << " ("
-                                         << fmt::format("{:0.2g}", sigmatofkMap / tofkMap * 100) << "%) " << tofpMap
-                                         << "+/-" << fmt::format("{:0.2g}", sigmatofpMap) << " ("
-                                         << fmt::format("{:0.2g}", sigmatofpMap / tofpMap * 100) << "%) ";
+                                         << "+/-" << std::format("{:0.2g}", sigmatofpiMap) << " ("
+                                         << std::format("{:0.2g}", sigmatofpiMap / tofpiMap * 100) << "%) " << tofkMap
+                                         << "+/-" << std::format("{:0.2g}", sigmatofkMap) << " ("
+                                         << std::format("{:0.2g}", sigmatofkMap / tofkMap * 100) << "%) " << tofpMap
+                                         << "+/-" << std::format("{:0.2g}", sigmatofpMap) << " ("
+                                         << std::format("{:0.2g}", sigmatofpMap / tofpMap * 100) << "%) ";
       } else {
         LogTrace("TrackExtenderWithMTD") << "Error in the MTD track refitting. This should not happen";
       }
diff --git a/SimTracker/TrackerMaterialAnalysis/plugins/BuildFile.xml b/SimTracker/TrackerMaterialAnalysis/plugins/BuildFile.xml
index 6a73331d0458c..c6e80acea3124 100644
--- a/SimTracker/TrackerMaterialAnalysis/plugins/BuildFile.xml
+++ b/SimTracker/TrackerMaterialAnalysis/plugins/BuildFile.xml
@@ -11,6 +11,7 @@
   <use name="SimDataFormats/ValidationFormats"/>
   <use name="SimG4Core/Watcher"/>
   <use name="boost"/>
+  <use name="fmt"/>
   <use name="geant4core"/>
   <use name="rootgpad"/>
   <flags EDM_PLUGIN="1"/>
@@ -28,6 +29,7 @@
   <use name="SimDataFormats/ValidationFormats"/>
   <use name="SimG4Core/Watcher"/>
   <use name="boost"/>
+  <use name="fmt"/>
   <use name="geant4core"/>
   <use name="rootgpad"/>
   <use name="DetectorDescription/DDCMS"/>
diff --git a/Utilities/StorageFactory/plugins/BuildFile.xml b/Utilities/StorageFactory/plugins/BuildFile.xml
index c8791c77d1445..40b63f5bfe9c0 100644
--- a/Utilities/StorageFactory/plugins/BuildFile.xml
+++ b/Utilities/StorageFactory/plugins/BuildFile.xml
@@ -10,7 +10,6 @@
   <use name="FWCore/ParameterSet"/>
   <use name="Utilities/StorageFactory"/>
   <use name="boost"/>
-  <use name="fmt"/>
   <flags EDM_PLUGIN="1"/>
   <flags cppflags="-D_FILE_OFFSET_BITS=64"/>
 </library>
diff --git a/Utilities/StorageFactory/plugins/StorageTracerProxy.cc b/Utilities/StorageFactory/plugins/StorageTracerProxy.cc
index e7a74ddb91004..49cd67da24a99 100644
--- a/Utilities/StorageFactory/plugins/StorageTracerProxy.cc
+++ b/Utilities/StorageFactory/plugins/StorageTracerProxy.cc
@@ -14,7 +14,7 @@
 #include <type_traits>
 
 #include <boost/algorithm/string.hpp>
-#include <fmt/format.h>
+#include <format>
 
 namespace edm::storage {
   class StorageTracerProxy : public Storage {
@@ -41,35 +41,35 @@ namespace edm::storage {
       using namespace std::literals::string_literals;
       file_.write(
           "# Format\n"s + "# --------\n"s + "# prefixes\n"s + "# #: comment\n"s +
-          fmt::format("# {}: file open\n", kOpen) + fmt::format("# {}: singular read\n", kRead) +
-          fmt::format("# {}: vector read\n", kReadv) +
-          fmt::format("# {}: vector read element of the preceding '{}' line\n", kReadvElement, kReadv) +
-          fmt::format("# {}: singular write\n", kWrite) + fmt::format("# {}: vector write\n", kWritev) +
-          fmt::format("# {}: vector write element of the preceding '{}' line\n", kWritevElement, kWritev) +
-          fmt::format("# {}: position (seek)\n", kPosition) + fmt::format("# {}: prefetch\n", kPrefetch) +
-          fmt::format("# {}: prefetch element of the preceding '{}' line\n", kPrefetch, kPrefetchElement) +
-          fmt::format("# {}: resize\n", kResize) + fmt::format("# {}: flush\n", kFlush) +
-          fmt::format("# {}: close\n", kClose) + "# --------\n"s + "# line formats\n"s +
-          fmt::format("# {} <id> <timestamp ms> <file name>\n", kOpen) +
-          fmt::format("# {} <id> <timestamp ms> <duration us> <offset B> <requested B> <actual B>\n", kRead) +
-          fmt::format(
+          std::format("# {}: file open\n", kOpen) + std::format("# {}: singular read\n", kRead) +
+          std::format("# {}: vector read\n", kReadv) +
+          std::format("# {}: vector read element of the preceding '{}' line\n", kReadvElement, kReadv) +
+          std::format("# {}: singular write\n", kWrite) + std::format("# {}: vector write\n", kWritev) +
+          std::format("# {}: vector write element of the preceding '{}' line\n", kWritevElement, kWritev) +
+          std::format("# {}: position (seek)\n", kPosition) + std::format("# {}: prefetch\n", kPrefetch) +
+          std::format("# {}: prefetch element of the preceding '{}' line\n", kPrefetch, kPrefetchElement) +
+          std::format("# {}: resize\n", kResize) + std::format("# {}: flush\n", kFlush) +
+          std::format("# {}: close\n", kClose) + "# --------\n"s + "# line formats\n"s +
+          std::format("# {} <id> <timestamp ms> <file name>\n", kOpen) +
+          std::format("# {} <id> <timestamp ms> <duration us> <offset B> <requested B> <actual B>\n", kRead) +
+          std::format(
               "# {} <id> <timestamp ms> <duration us> <requested total B> <actual total B> <number of elements>\n",
               kReadv) +
-          fmt::format("# {} <index> <offset B> <requested B>\n", kReadvElement) +
-          fmt::format("# {} <id> <timestamp ms> <duration us> <offset B> <requested B> <actual B>\n", kWrite) +
-          fmt::format(
+          std::format("# {} <index> <offset B> <requested B>\n", kReadvElement) +
+          std::format("# {} <id> <timestamp ms> <duration us> <offset B> <requested B> <actual B>\n", kWrite) +
+          std::format(
               "# {} <id> <timestamp ms> <duration us> <requested total B> <actual total B> <number of elements>\n",
               kWritev) +
-          fmt::format("# {} <index> <offset B> <requested B>\n", kWritevElement) +
-          fmt::format("# {} <id> <timestamp ms> <duration us> <offset B> <whence>\n", kPosition) +
-          fmt::format("# {} <id> <timestamp ms> <duration us> <requested total B> <number of elements> <supported?>\n",
+          std::format("# {} <index> <offset B> <requested B>\n", kWritevElement) +
+          std::format("# {} <id> <timestamp ms> <duration us> <offset B> <whence>\n", kPosition) +
+          std::format("# {} <id> <timestamp ms> <duration us> <requested total B> <number of elements> <supported?>\n",
                       kPrefetch) +
-          fmt::format("# {} <index> <offset B> <requested B>\n", kPrefetchElement) +
-          fmt::format("# {} <id> <timestamp ms> <duration us> <size B>\n", kResize) +
-          fmt::format("# {} <id> <timestamp ms> <duration us>\n", kFlush) +
-          fmt::format("# {} <id> <timestamp ms> <duration us>\n", kClose) + "# --------\n"s);
+          std::format("# {} <index> <offset B> <requested B>\n", kPrefetchElement) +
+          std::format("# {} <id> <timestamp ms> <duration us> <size B>\n", kResize) +
+          std::format("# {} <id> <timestamp ms> <duration us>\n", kFlush) +
+          std::format("# {} <id> <timestamp ms> <duration us>\n", kClose) + "# --------\n"s);
       auto const entryId = idCounter_.fetch_add(1);
-      file_.write(fmt::format("{} {} {} {}\n",
+      file_.write(std::format("{} {} {} {}\n",
                               kOpen,
                               entryId,
                               std::chrono::round<std::chrono::milliseconds>(now().time_since_epoch()).count(),
@@ -80,13 +80,13 @@ namespace edm::storage {
     IOSize read(void* into, IOSize n) override {
       auto const offset = baseStorage_->position();
       auto const [result, message] = operate([this, into, n]() { return baseStorage_->read(into, n); });
-      file_.write(fmt::format("{} {} {} {} {}\n", kRead, message, offset, n, result));
+      file_.write(std::format("{} {} {} {} {}\n", kRead, message, offset, n, result));
       return result;
     }
 
     IOSize read(void* into, IOSize n, IOOffset pos) override {
       auto const [result, message] = operate([this, into, n, pos]() { return baseStorage_->read(into, n, pos); });
-      file_.write(fmt::format("{} {} {} {} {}\n", kRead, message, pos, n, result));
+      file_.write(std::format("{} {} {} {} {}\n", kRead, message, pos, n, result));
       return result;
     }
 
@@ -96,11 +96,11 @@ namespace edm::storage {
       std::string elements;
       IOSize total = 0;
       for (IOSize i = 0; i < n; ++i) {
-        elements += fmt::format("{} {} {} {}\n", kReadvElement, i, offset, into[i].size());
+        elements += std::format("{} {} {} {}\n", kReadvElement, i, offset, into[i].size());
         total += into[i].size();
         offset += into[i].size();
       }
-      file_.write(fmt::format("{} {} {} {} {}\n", kReadv, message, total, result, n) + elements);
+      file_.write(std::format("{} {} {} {} {}\n", kReadv, message, total, result, n) + elements);
       return result;
     }
 
@@ -109,23 +109,23 @@ namespace edm::storage {
       std::string elements;
       IOSize total = 0;
       for (IOSize i = 0; i < n; ++i) {
-        elements += fmt::format("{} {} {} {}\n", kReadvElement, i, into[i].offset(), into[i].size());
+        elements += std::format("{} {} {} {}\n", kReadvElement, i, into[i].offset(), into[i].size());
         total += into[i].size();
       }
-      file_.write(fmt::format("{} {} {} {} {}\n", kReadv, message, total, result, n) + elements);
+      file_.write(std::format("{} {} {} {} {}\n", kReadv, message, total, result, n) + elements);
       return result;
     }
 
     IOSize write(const void* from, IOSize n) override {
       auto const offset = baseStorage_->position();
       auto const [result, message] = operate([this, from, n]() { return baseStorage_->write(from, n); });
-      file_.write(fmt::format("{} {} {} {} {}\n", kWrite, message, offset, n, result));
+      file_.write(std::format("{} {} {} {} {}\n", kWrite, message, offset, n, result));
       return result;
     }
 
     IOSize write(const void* from, IOSize n, IOOffset pos) override {
       auto const [result, message] = operate([this, from, n, pos]() { return baseStorage_->write(from, n, pos); });
-      file_.write(fmt::format("{} {} {} {} {}\n", kWrite, message, pos, n, result));
+      file_.write(std::format("{} {} {} {} {}\n", kWrite, message, pos, n, result));
       return result;
     }
 
@@ -135,11 +135,11 @@ namespace edm::storage {
       std::string elements;
       IOSize total = 0;
       for (IOSize i = 0; i < n; ++i) {
-        elements += fmt::format("{} {} {} {}\n", kWritevElement, i, offset, from[i].size());
+        elements += std::format("{} {} {} {}\n", kWritevElement, i, offset, from[i].size());
         total += from[i].size();
         offset += from[i].size();
       }
-      file_.write(fmt::format("{} {} {} {} {}\n", kWritev, message, total, result, n) + elements);
+      file_.write(std::format("{} {} {} {} {}\n", kWritev, message, total, result, n) + elements);
       return result;
     }
 
@@ -148,33 +148,33 @@ namespace edm::storage {
       std::string elements;
       IOSize total = 0;
       for (IOSize i = 0; i < n; ++i) {
-        elements += fmt::format("{} {} {} {}\n", kWritevElement, i, from[i].offset(), from[i].size());
+        elements += std::format("{} {} {} {}\n", kWritevElement, i, from[i].offset(), from[i].size());
         total += from[i].size();
       }
-      file_.write(fmt::format("{} {} {} {} {}\n", kWritev, message, total, result, n) + elements);
+      file_.write(std::format("{} {} {} {} {}\n", kWritev, message, total, result, n) + elements);
       return result;
     }
 
     IOOffset position(IOOffset offset, Relative whence) override {
       auto const [result, message] =
           operate([this, offset, whence]() { return baseStorage_->position(offset, whence); });
-      file_.write(fmt::format("{} {} {} {}\n", kPosition, message, offset, static_cast<int>(whence)));
+      file_.write(std::format("{} {} {} {}\n", kPosition, message, offset, static_cast<int>(whence)));
       return result;
     }
 
     void resize(IOOffset size) override {
       auto const message = operate([this, size]() { return baseStorage_->resize(size); });
-      file_.write(fmt::format("{} {} {}\n", kResize, message, size));
+      file_.write(std::format("{} {} {}\n", kResize, message, size));
     }
 
     void flush() override {
       auto const message = operate([this]() { return baseStorage_->flush(); });
-      file_.write(fmt::format("{} {}\n", kFlush, message));
+      file_.write(std::format("{} {}\n", kFlush, message));
     }
 
     void close() override {
       auto const message = operate([this]() { return baseStorage_->close(); });
-      file_.write(fmt::format("{} {}\n", kClose, message));
+      file_.write(std::format("{} {}\n", kClose, message));
     }
 
     bool prefetch(const IOPosBuffer* what, IOSize n) override {
@@ -182,10 +182,10 @@ namespace edm::storage {
       std::string elements;
       IOSize total = 0;
       for (IOSize i = 0; i < n; ++i) {
-        elements += fmt::format("{} {} {} {}\n", kPrefetchElement, i, what[i].offset(), what[i].size());
+        elements += std::format("{} {} {} {}\n", kPrefetchElement, i, what[i].offset(), what[i].size());
         total += what[i].size();
       }
-      file_.write(fmt::format("{} {} {} {} {}\n", kPrefetch, message, total, n, value) + elements);
+      file_.write(std::format("{} {} {} {} {}\n", kPrefetch, message, total, n, value) + elements);
       return value;
     }
 
@@ -198,7 +198,7 @@ namespace edm::storage {
       auto const end = now();
       LogTrace("IOTrace").format("IOTrace {} id {}", traceId_, id);
       return std::tuple(result,
-                        fmt::format("{} {} {}",
+                        std::format("{} {} {}",
                                     id,
                                     std::chrono::round<std::chrono::milliseconds>(begin.time_since_epoch()).count(),
                                     std::chrono::round<std::chrono::microseconds>(end - begin).count()));
@@ -212,7 +212,7 @@ namespace edm::storage {
       func();
       auto const end = now();
       LogTrace("IOTrace").format("IOTrace {} id {}", traceId_, id);
-      return fmt::format("{} {} {}",
+      return std::format("{} {} {}",
                          id,
                          std::chrono::round<std::chrono::milliseconds>(begin.time_since_epoch()).count(),
                          std::chrono::round<std::chrono::microseconds>(end - begin).count());
diff --git a/Validation/RecoJets/plugins/JetTester.cc b/Validation/RecoJets/plugins/JetTester.cc
index 622854757e82d..5d3e896ae9db6 100644
--- a/Validation/RecoJets/plugins/JetTester.cc
+++ b/Validation/RecoJets/plugins/JetTester.cc
@@ -6,6 +6,7 @@
 
 #include "JetTester.h"
 #include <vector>
+#include <format>
 
 using namespace edm;
 using namespace reco;
@@ -459,59 +460,59 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
     const auto& [etaRegion, etaLabel, etaMin, etaMax] = etaInfo[j];
 
     mNJets_EtaBins[j] = ibooker.book1D(
-        fmt::format("NJets_{}", etaRegion),
-        fmt::format("Number of jets p_{{T}}>{} GeV - {};# jets;# events", int(mRecoJetPtThreshold), etaLabel),
+        std::format("NJets_{}", etaRegion),
+        std::format("Number of jets p_{{T}}>{} GeV - {};# jets;# events", int(mRecoJetPtThreshold), etaLabel),
         15,
         0,
         15);
     mGenPt_EtaBins[j] = ibooker.book1D(
-        fmt::format("GenPt_{}", etaRegion),
-        fmt::format("Gen Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mMatchGenPtThreshold), etaLabel),
+        std::format("GenPt_{}", etaRegion),
+        std::format("Gen Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mMatchGenPtThreshold), etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1]);
 
     mJetPt_EtaBins[j] = ibooker.book1D(
-        fmt::format("JetPt_{}", etaRegion),
-        fmt::format("Reco Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mRecoJetPtThreshold), etaLabel),
+        std::format("JetPt_{}", etaRegion),
+        std::format("Reco Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mRecoJetPtThreshold), etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1]);
 
-    mMatchedJetPt_EtaBins[j] = ibooker.book1D(fmt::format("MatchedJetPt_{}", etaRegion),
-                                              fmt::format("Matched Jets - {};p_{{T}} [GeV];# jets", etaLabel),
+    mMatchedJetPt_EtaBins[j] = ibooker.book1D(std::format("MatchedJetPt_{}", etaRegion),
+                                              std::format("Matched Jets - {};p_{{T}} [GeV];# jets", etaLabel),
                                               n_PtBins,
                                               PtRange[0],
                                               PtRange[1]);
-    mMatchedGenPt_EtaBins[j] = ibooker.book1D(fmt::format("MatchedGenPt_{}", etaRegion),
-                                              fmt::format("Matched Gen Jets - {};p_{{T}} [GeV];# jets", etaLabel),
+    mMatchedGenPt_EtaBins[j] = ibooker.book1D(std::format("MatchedGenPt_{}", etaRegion),
+                                              std::format("Matched Gen Jets - {};p_{{T}} [GeV];# jets", etaLabel),
                                               n_PtBins,
                                               PtRange[0],
                                               PtRange[1]);
 
     mDuplicatesGenPt_EtaBins[j] =
-        ibooker.book1D(fmt::format("DuplicatesGenPt_{}", etaRegion),
-                       fmt::format("Reco jets matched to multiple gen jets [{}];p_{{T}} [GeV];# Duplicates", etaLabel),
+        ibooker.book1D(std::format("DuplicatesGenPt_{}", etaRegion),
+                       std::format("Reco jets matched to multiple gen jets [{}];p_{{T}} [GeV];# Duplicates", etaLabel),
                        n_PtBins,
                        PtRange[0],
                        PtRange[1]);
     mDuplicatesJetPt_EtaBins[j] =
-        ibooker.book1D(fmt::format("DuplicatesJetPt_{}", etaRegion),
-                       fmt::format("Gen jets matched to multiple reco jets [{}];p_{{T}} [GeV];# Duplicates", etaLabel),
+        ibooker.book1D(std::format("DuplicatesJetPt_{}", etaRegion),
+                       std::format("Gen jets matched to multiple reco jets [{}];p_{{T}} [GeV];# Duplicates", etaLabel),
                        n_PtBins,
                        PtRange[0],
                        PtRange[1]);
 
     h_JetPtRecoOverGen[j] =
-        ibooker.book1D(fmt::format("h_PtRecoOverGen_{}", etaRegion),
-                       fmt::format("Response Reco Jets - {};p_{{T}}^{{reco}}/p_{{T}}^{{gen}};# jets", etaLabel),
+        ibooker.book1D(std::format("h_PtRecoOverGen_{}", etaRegion),
+                       std::format("Response Reco Jets - {};p_{{T}}^{{reco}}/p_{{T}}^{{gen}};# jets", etaLabel),
                        n_RespBins,
                        RespRange[0],
                        RespRange[1]);
 
     h2d_JetPtRecoOverGen_vs_GenPhi_EtaBins[j] =
-        ibooker.book2D(fmt::format("h2d_PtRecoOverGen_GenPhi_{}", etaRegion),
-                       fmt::format("Response Reco Jets - {};#phi^{{gen}};p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        ibooker.book2D(std::format("h2d_PtRecoOverGen_GenPhi_{}", etaRegion),
+                       std::format("Response Reco Jets - {};#phi^{{gen}};p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
                        n_PhiBins,
                        PhiRange[0],
                        PhiRange[1],
@@ -519,8 +520,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
                        RespRange[0],
                        RespRange[1]);
     h2d_JetPtRecoOverGen_vs_GenPt_EtaBins[j] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_GenPt_{}", etaRegion),
-        fmt::format("Response Reco Jets - {};p_{{T}}^{{gen}};p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        std::format("h2d_PtRecoOverGen_GenPt_{}", etaRegion),
+        std::format("Response Reco Jets - {};p_{{T}}^{{gen}};p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -529,8 +530,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         RespRange[1]);
 
     h2d_chHadMult_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_chHadMult_pt_{}", etaRegion),
-        fmt::format("Profiled charged HAD multiplicity - {};p_{{T}}^{{reco}};charged HAD multiplicity", etaLabel),
+        std::format("h2d_chHadMult_pt_{}", etaRegion),
+        std::format("Profiled charged HAD multiplicity - {};p_{{T}}^{{reco}};charged HAD multiplicity", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -538,8 +539,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         50);
     h2d_neHadMult_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_neHadMult_pt_{}", etaRegion),
-        fmt::format("Profiled neutral HAD multiplicity - {};p_{{T}}^{{reco}};neutral HAD multiplicity", etaLabel),
+        std::format("h2d_neHadMult_pt_{}", etaRegion),
+        std::format("Profiled neutral HAD multiplicity - {};p_{{T}}^{{reco}};neutral HAD multiplicity", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -547,8 +548,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         50);
     h2d_chMult_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_chMult_pt_{}", etaRegion),
-        fmt::format("Profiled charged multiplicity - {};p_{{T}}^{{reco}};charged multiplicity", etaLabel),
+        std::format("h2d_chMult_pt_{}", etaRegion),
+        std::format("Profiled charged multiplicity - {};p_{{T}}^{{reco}};charged multiplicity", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -556,8 +557,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         50);
     h2d_neMult_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_neMult_pt_{}", etaRegion),
-        fmt::format("Profiled neutral multiplicity - {};p_{{T}}^{{reco}};neutral EM multiplicity", etaLabel),
+        std::format("h2d_neMult_pt_{}", etaRegion),
+        std::format("Profiled neutral multiplicity - {};p_{{T}}^{{reco}};neutral EM multiplicity", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -565,8 +566,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         50);
     h2d_phoMult_vs_pt[j] =
-        ibooker.book2D(fmt::format("h2d_phoMult_pt_{}", etaRegion),
-                       fmt::format("Profiled photon multiplicity - {};p_{{T}}^{{reco}};photon multiplicity", etaLabel),
+        ibooker.book2D(std::format("h2d_phoMult_pt_{}", etaRegion),
+                       std::format("Profiled photon multiplicity - {};p_{{T}}^{{reco}};photon multiplicity", etaLabel),
                        n_PtBins,
                        PtRange[0],
                        PtRange[1],
@@ -575,8 +576,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
                        15);
 
     h2d_chHad_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_chHad_pt_{}", etaRegion),
-        fmt::format("Profiled charged HAD energy fraction - {};p_{{T}}^{{reco}};charged HAD energy fraction", etaLabel),
+        std::format("h2d_chHad_pt_{}", etaRegion),
+        std::format("Profiled charged HAD energy fraction - {};p_{{T}}^{{reco}};charged HAD energy fraction", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -584,8 +585,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         1);
     h2d_neHad_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_neHad_pt_{}", etaRegion),
-        fmt::format("Profiled neutral HAD energy fraction - {};p_{{T}}^{{reco}};neutral HAD energy fraction", etaLabel),
+        std::format("h2d_neHad_pt_{}", etaRegion),
+        std::format("Profiled neutral HAD energy fraction - {};p_{{T}}^{{reco}};neutral HAD energy fraction", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -593,8 +594,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         1);
     h2d_chEm_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_chEm_pt_{}", etaRegion),
-        fmt::format("Profiled charged EM energy fraction - {};p_{{T}}^{{reco}};charged EM energy fraction", etaLabel),
+        std::format("h2d_chEm_pt_{}", etaRegion),
+        std::format("Profiled charged EM energy fraction - {};p_{{T}}^{{reco}};charged EM energy fraction", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -602,8 +603,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         0,
         1);
     h2d_neEm_vs_pt[j] = ibooker.book2D(
-        fmt::format("h2d_neEm_pt_{}", etaRegion),
-        fmt::format("Profiled neutral EM energy fraction - {};p_{{T}}^{{reco}};neutral EM energy fraction", etaLabel),
+        std::format("h2d_neEm_pt_{}", etaRegion),
+        std::format("Profiled neutral EM energy fraction - {};p_{{T}}^{{reco}};neutral EM energy fraction", etaLabel),
         n_PtBins,
         PtRange[0],
         PtRange[1],
@@ -612,8 +613,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         1);
 
     h2d_JetPtRecoOverGen_vs_chHad[j] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_chHad_{}", etaRegion),
-        fmt::format("Response Reco Jets - {};charged HAD energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        std::format("h2d_PtRecoOverGen_chHad_{}", etaRegion),
+        std::format("Response Reco Jets - {};charged HAD energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
         30,
         0,
         1,
@@ -621,8 +622,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         RespRange[0],
         RespRange[1]);
     h2d_JetPtRecoOverGen_vs_neHad[j] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_neHad_{}", etaRegion),
-        fmt::format("Response Reco Jets - {};neutral HAD energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        std::format("h2d_PtRecoOverGen_neHad_{}", etaRegion),
+        std::format("Response Reco Jets - {};neutral HAD energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
         30,
         0,
         1,
@@ -630,8 +631,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         RespRange[0],
         RespRange[1]);
     h2d_JetPtRecoOverGen_vs_chEm[j] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_chEm_{}", etaRegion),
-        fmt::format("Response Reco Jets - {};charged EM energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        std::format("h2d_PtRecoOverGen_chEm_{}", etaRegion),
+        std::format("Response Reco Jets - {};charged EM energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
         30,
         0,
         1,
@@ -639,8 +640,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         RespRange[0],
         RespRange[1]);
     h2d_JetPtRecoOverGen_vs_neEm[j] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_neEm_{}", etaRegion),
-        fmt::format("Response Reco Jets - {};neutral EM energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        std::format("h2d_PtRecoOverGen_neEm_{}", etaRegion),
+        std::format("Response Reco Jets - {};neutral EM energy Fraction;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
         30,
         0,
         1,
@@ -648,8 +649,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
         RespRange[0],
         RespRange[1]);
     h2d_JetPtRecoOverGen_vs_nCost[j] =
-        ibooker.book2D(fmt::format("h2d_PtRecoOverGen_nCost_{}", etaRegion),
-                       fmt::format("Response Reco Jets - {};# constituents;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
+        ibooker.book2D(std::format("h2d_PtRecoOverGen_nCost_{}", etaRegion),
+                       std::format("Response Reco Jets - {};# constituents;p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", etaLabel),
                        100,
                        0,
                        100,
@@ -660,9 +661,9 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
     for (int i = 0; i < ptSize; ++i) {
       int ptMin = int(ptBins_[i]);
       int ptMax = int(ptBins_[i + 1]);
-      auto h_name_RoG = fmt::format("h_PtRecoOverGen_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
+      auto h_name_RoG = std::format("h_PtRecoOverGen_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
       auto h_title_RoG =
-          fmt::format("Response Reco Jets - {} - {}<p_{{T}}^{{gen}}<{};p_{{T}}^{{reco}}/p_{{T}}^{{gen}};# jets",
+          std::format("Response Reco Jets - {} - {}<p_{{T}}^{{gen}}<{};p_{{T}}^{{reco}}/p_{{T}}^{{gen}};# jets",
                       etaLabel,
                       ptMin,
                       ptMax);
@@ -675,8 +676,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
     int ptMin = int(ptBins_[i]);
     int ptMax = int(ptBins_[i + 1]);
     h2d_JetPtRecoOverGen_vs_GenEta_ptBins[i] = ibooker.book2D(
-        fmt::format("h2d_PtRecoOverGen_GenEta_Pt{}_{}", ptMin, ptMax),
-        fmt::format(
+        std::format("h2d_PtRecoOverGen_GenEta_Pt{}_{}", ptMin, ptMax),
+        std::format(
             "Response Reco Jets - {}<p_{{T}}^{{gen}}<{};#eta^{{gen}};p_{{T}}^{{reco}}/p_{{T}}^{{gen}}", ptMin, ptMax),
         n_EtaBins,
         EtaRange[0],
@@ -787,31 +788,31 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
       const auto& [etaRegion, etaLabel, etaMin, etaMax] = etaInfo[j];
 
       mCorrJetPt_EtaBins[j] = ibooker.book1D(
-          fmt::format("CorrJetPt_{}", etaRegion),
-          fmt::format("Corr Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mRecoJetPtThreshold), etaLabel),
+          std::format("CorrJetPt_{}", etaRegion),
+          std::format("Corr Jets p_{{T}}>{} GeV - {};p_{{T}} [GeV];# jets", int(mRecoJetPtThreshold), etaLabel),
           n_PtBins,
           PtRange[0],
           PtRange[1]);
-      mMatchedCorrPt_EtaBins[j] = ibooker.book1D(fmt::format("MatchedCorrPt_{}", etaRegion),
-                                                 fmt::format("Matched Corr Jets - {};p_{{T}} [GeV];# jets", etaLabel),
+      mMatchedCorrPt_EtaBins[j] = ibooker.book1D(std::format("MatchedCorrPt_{}", etaRegion),
+                                                 std::format("Matched Corr Jets - {};p_{{T}} [GeV];# jets", etaLabel),
                                                  n_PtBins,
                                                  PtRange[0],
                                                  PtRange[1]);
       h_JetPtCorrOverGen[j] =
-          ibooker.book1D(fmt::format("h_JetPtCorrOverGen_{}", etaRegion),
-                         fmt::format("Response Corr Jets - {};p_{{T}}^{{corr}}/p_{{T}}^{{gen}};# jets", etaLabel),
+          ibooker.book1D(std::format("h_JetPtCorrOverGen_{}", etaRegion),
+                         std::format("Response Corr Jets - {};p_{{T}}^{{corr}}/p_{{T}}^{{gen}};# jets", etaLabel),
                          n_RespBins,
                          RespRange[0],
                          RespRange[1]);
       h_JetPtCorrOverReco[j] =
-          ibooker.book1D(fmt::format("h_JetPtCorrOverReco_{}", etaRegion),
-                         fmt::format("Response Corr Jets - {};p_{{T}}^{{corr}}/p_{{T}}^{{reco}};# jets", etaLabel),
+          ibooker.book1D(std::format("h_JetPtCorrOverReco_{}", etaRegion),
+                         std::format("Response Corr Jets - {};p_{{T}}^{{corr}}/p_{{T}}^{{reco}};# jets", etaLabel),
                          n_RespBins,
                          RespRange[0],
                          RespRange[1]);
       h2d_JetPtCorrOverGen_vs_GenPhi_EtaBins[j] =
-          ibooker.book2D(fmt::format("h2d_PtCorrOverGen_GenPhi_{}", etaRegion),
-                         fmt::format("Response Corr Jets - {};#phi^{{gen}};p_{{T}}^{{corr}}/p_{{T}}^{{gen}}", etaLabel),
+          ibooker.book2D(std::format("h2d_PtCorrOverGen_GenPhi_{}", etaRegion),
+                         std::format("Response Corr Jets - {};#phi^{{gen}};p_{{T}}^{{corr}}/p_{{T}}^{{gen}}", etaLabel),
                          n_PhiBins,
                          PhiRange[0],
                          PhiRange[1],
@@ -819,8 +820,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
                          RespRange[0],
                          RespRange[1]);
       h2d_JetPtCorrOverGen_vs_GenPt_EtaBins[j] = ibooker.book2D(
-          fmt::format("h2d_PtCorrOverGen_GenPt_{}", etaRegion),
-          fmt::format("Response Corr Jets - {};p_{{T}}^{{gen}};p_{{T}}^{{corr}}/p_{{T}}^{{gen}}", etaLabel),
+          std::format("h2d_PtCorrOverGen_GenPt_{}", etaRegion),
+          std::format("Response Corr Jets - {};p_{{T}}^{{gen}};p_{{T}}^{{corr}}/p_{{T}}^{{gen}}", etaLabel),
           n_PtBins,
           PtRange[0],
           PtRange[1],
@@ -828,8 +829,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
           RespRange[0],
           RespRange[1]);
       h2d_JetPtCorrOverReco_vs_Phi_EtaBins[j] = ibooker.book2D(
-          fmt::format("h2d_PtCorrOverReco_Phi_{}", etaRegion),
-          fmt::format("Response Corr Jets - {};#phi^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}", etaLabel),
+          std::format("h2d_PtCorrOverReco_Phi_{}", etaRegion),
+          std::format("Response Corr Jets - {};#phi^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}", etaLabel),
           n_PhiBins,
           PhiRange[0],
           PhiRange[1],
@@ -837,8 +838,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
           RespRange[0],
           RespRange[1]);
       h2d_JetPtCorrOverReco_vs_Pt_EtaBins[j] = ibooker.book2D(
-          fmt::format("h2d_PtCorrOverReco_Pt_{}", etaRegion),
-          fmt::format("Response Corr Jets - {};p_{{T}}^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}", etaLabel),
+          std::format("h2d_PtCorrOverReco_Pt_{}", etaRegion),
+          std::format("Response Corr Jets - {};p_{{T}}^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}", etaLabel),
           n_PtBins,
           PtRange[0],
           PtRange[1],
@@ -849,18 +850,18 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
       for (int i = 0; i < ptSize; ++i) {
         double ptMin = ptBins_[i];
         double ptMax = ptBins_[i + 1];
-        auto h_name_CoG = fmt::format("h_PtCorrOverGen_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
+        auto h_name_CoG = std::format("h_PtCorrOverGen_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
         auto h_title_CoG =
-            fmt::format("Response Corr Jets - {} - {}<p_{{T}}^{{gen}}<{};p_{{T}}^{{corr}}/p_{{T}}^{{gen}};# jets",
+            std::format("Response Corr Jets - {} - {}<p_{{T}}^{{gen}}<{};p_{{T}}^{{corr}}/p_{{T}}^{{gen}};# jets",
                         etaLabel,
                         ptMin,
                         ptMax);
         hVector_JetPtCorrOverGen_ptBins[j][i] =
             ibooker.book1D(h_name_CoG, h_title_CoG, n_RespBins, RespRange[0], RespRange[1]);
 
-        auto h_name_CoR = fmt::format("h_PtCorrOverReco_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
+        auto h_name_CoR = std::format("h_PtCorrOverReco_{}_Pt{}_{}", etaRegion, ptMin, ptMax);
         auto h_title_CoR =
-            fmt::format("Response Corr Jets - {} - {}<p_{{T}}^{{reco}}<{};p_{{T}}^{{corr}}/p_{{T}}^{{reco}};# jets",
+            std::format("Response Corr Jets - {} - {}<p_{{T}}^{{reco}}<{};p_{{T}}^{{corr}}/p_{{T}}^{{reco}};# jets",
                         etaLabel,
                         ptMin,
                         ptMax);
@@ -873,8 +874,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
       int ptMin = int(ptBins_[i]);
       int ptMax = int(ptBins_[i + 1]);
       h2d_JetPtCorrOverGen_vs_GenEta_ptBins[i] = ibooker.book2D(
-          fmt::format("h2d_PtCorrOverGen_GenEta_Pt{}_{}", ptMin, ptMax),
-          fmt::format(
+          std::format("h2d_PtCorrOverGen_GenEta_Pt{}_{}", ptMin, ptMax),
+          std::format(
               "Response Corr Jets - {}<p_{{T}}^{{gen}}<{};#eta^{{gen}};p_{{T}}^{{corr}}/p_{{T}}^{{gen}}", ptMin, ptMax),
           n_EtaBins,
           EtaRange[0],
@@ -883,8 +884,8 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
           RespRange[0],
           RespRange[1]);
       h2d_JetPtCorrOverReco_vs_Eta_ptBins[i] = ibooker.book2D(
-          fmt::format("h2d_PtCorrOverReco_Eta_Pt{}_{}", ptMin, ptMax),
-          fmt::format("Response Corr Jets - {}<p_{{T}}^{{reco}}<{};#eta^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}",
+          std::format("h2d_PtCorrOverReco_Eta_Pt{}_{}", ptMin, ptMax),
+          std::format("Response Corr Jets - {}<p_{{T}}^{{reco}}<{};#eta^{{reco}};p_{{T}}^{{corr}}/p_{{T}}^{{reco}}",
                       ptMin,
                       ptMax),
           n_EtaBins,
@@ -909,7 +910,7 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
   // Some jet algebra
   mMjj = ibooker.book1D("Mjj", "Mjj", 100, 0, 2000);
   mNJets = ibooker.book1D(
-      "NJets", fmt::format("Number of jets p_{{T}}>{} GeV;# jets;# events", mRecoJetPtThreshold), 15, 0, 15);
+      "NJets", std::format("Number of jets p_{{T}}>{} GeV;# jets;# events", mRecoJetPtThreshold), 15, 0, 15);
   mNJetsPt1 = ibooker.bookProfile(
       "NJetsPt1", "Number of jets above Pt threshold;p_{T} [GeV];# jets", 100, 0, 200, 100, 0, 50, "s");
   mNJetsPt2 = ibooker.bookProfile(
@@ -971,26 +972,26 @@ void JetTester::bookHistograms(DQMStore::IBooker& ibooker, edm::Run const& iRun,
     for (size_t j = 0; j < etaInfo.size(); ++j) {
       const auto& [etaRegion, etaLabel, etaMin, etaMax] = etaInfo[j];
       photonMultiplicity_EtaBins[j] = ibooker.book1D(
-          fmt::format("photonMultiplicity_{}", etaRegion), fmt::format("photonMultiplicity_{}", etaRegion), 15, 0, 15);
-      electronMultiplicity_EtaBins[j] = ibooker.book1D(fmt::format("electronMultiplicity_{}", etaRegion),
-                                                       fmt::format("electronMultiplicity_{}", etaRegion),
+          std::format("photonMultiplicity_{}", etaRegion), std::format("photonMultiplicity_{}", etaRegion), 15, 0, 15);
+      electronMultiplicity_EtaBins[j] = ibooker.book1D(std::format("electronMultiplicity_{}", etaRegion),
+                                                       std::format("electronMultiplicity_{}", etaRegion),
                                                        15,
                                                        0,
                                                        15);
-      neutralHadronMultiplicity_EtaBins[j] = ibooker.book1D(fmt::format("neutralHadronMultiplicity_{}", etaRegion),
-                                                            fmt::format("neutralHadronMultiplicity_{}", etaRegion),
+      neutralHadronMultiplicity_EtaBins[j] = ibooker.book1D(std::format("neutralHadronMultiplicity_{}", etaRegion),
+                                                            std::format("neutralHadronMultiplicity_{}", etaRegion),
                                                             50,
                                                             0,
                                                             50);
       neutralMultiplicity_EtaBins[j] = ibooker.book1D(
-          fmt::format("neutralMultiplicity_{}", etaRegion), fmt::format("neutralMultiplicity_{}", etaRegion), 50, 0, 50);
-      chargedHadronMultiplicity_EtaBins[j] = ibooker.book1D(fmt::format("chargedHadronMultiplicity_{}", etaRegion),
-                                                            fmt::format("chargedHadronMultiplicity_{}", etaRegion),
+          std::format("neutralMultiplicity_{}", etaRegion), std::format("neutralMultiplicity_{}", etaRegion), 50, 0, 50);
+      chargedHadronMultiplicity_EtaBins[j] = ibooker.book1D(std::format("chargedHadronMultiplicity_{}", etaRegion),
+                                                            std::format("chargedHadronMultiplicity_{}", etaRegion),
                                                             50,
                                                             0,
                                                             50);
-      chargedMultiplicity_EtaBins[j] = ibooker.book1D(fmt::format("chargedMultiplicity_{}", etaRegion),
-                                                      fmt::format("chargedMultiplicity_{}", etaRegion),
+      chargedMultiplicity_EtaBins[j] = ibooker.book1D(std::format("chargedMultiplicity_{}", etaRegion),
+                                                      std::format("chargedMultiplicity_{}", etaRegion),
                                                       100,
                                                       0,
                                                       100);
diff --git a/Validation/RecoMET/plugins/METTester.cc b/Validation/RecoMET/plugins/METTester.cc
index 02e2c54eb1f1e..74ec29f5a881e 100644
--- a/Validation/RecoMET/plugins/METTester.cc
+++ b/Validation/RecoMET/plugins/METTester.cc
@@ -1,4 +1,5 @@
 #include "METTester.h"
+#include <format>
 
 using namespace reco;
 using namespace std;
@@ -98,7 +99,7 @@ std::string METTester::binStr(float left, float right, bool roundInt) {
   if (roundInt) {
     out = std::to_string((int)left) + "to" + std::to_string((int)right);
   } else {
-    out = fmt::format("{:.2f}", left) + "to" + fmt::format("{:.2f}", right);
+    out = std::format("{:.2f}", left) + "to" + std::format("{:.2f}", right);
     std::replace(out.begin(), out.end(), '.', 'p');
   }
   return out;