diff --git a/build.gradle b/build.gradle
index 4e7734cd..313acc49 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,13 +1,16 @@
+import dev.sorn.fmp4j.CoveragePlugin
+import dev.sorn.fmp4j.SnakeCaseMethodFormatter
+
 plugins {
     id 'java-library'
     id 'java-test-fixtures'
     id 'checkstyle'
     id 'jacoco'
     id 'com.vanniktech.maven.publish' version '0.34.0'
-    id 'com.diffplug.spotless' version '7.2.0'
+    id 'com.diffplug.spotless'
 }
 
-apply plugin: dev.sorn.fmp4j.CoveragePlugin
+apply plugin: CoveragePlugin
 
 group = 'dev.sorn.fmp4j'
 version = projectVersion
@@ -18,6 +21,12 @@ java {
     }
 }
 
+spotless {
+    java {
+        addStep(new SnakeCaseMethodFormatter())
+    }
+}
+
 repositories {
     mavenCentral()
 }
@@ -28,6 +37,8 @@ dependencies {
     implementation("com.fasterxml.jackson.core:jackson-databind:${jacksonVersion}")
     implementation("org.apache.httpcomponents.client5:httpclient5:${apacheHttpComponentsVersion}")
     implementation("org.apache.commons:commons-lang3:${apacheCommonsVersion}")
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:${spotlessVersion}")
+
     testImplementation("org.mockito:mockito-core:${mockitoCoreVersion}")
     testImplementation("org.mockito:mockito-junit-jupiter:${mockitoJunitVersion}")
     testImplementation(platform("org.junit:junit-bom:${junitVersion}"))
diff --git a/buildSrc/build.gradle b/buildSrc/build.gradle
index 2d087cae..ae68cb9d 100644
--- a/buildSrc/build.gradle
+++ b/buildSrc/build.gradle
@@ -9,4 +9,6 @@ repositories {
 dependencies {
     implementation gradleApi()
     implementation localGroovy()
+    implementation("com.diffplug.spotless:spotless-plugin-gradle:${spotlessVersion}")
+    implementation("com.github.javaparser:javaparser-core:${javaparserVersion}")
 }
\ No newline at end of file
diff --git a/buildSrc/gradle.properties b/buildSrc/gradle.properties
new file mode 100644
index 00000000..10a7177e
--- /dev/null
+++ b/buildSrc/gradle.properties
@@ -0,0 +1,2 @@
+spotlessVersion=7.2.0
+javaparserVersion=3.27.0
\ No newline at end of file
diff --git a/buildSrc/src/main/groovy/CoveragePlugin.groovy b/buildSrc/src/main/groovy/dev/sorn/fmp4j/CoveragePlugin.groovy
similarity index 100%
rename from buildSrc/src/main/groovy/CoveragePlugin.groovy
rename to buildSrc/src/main/groovy/dev/sorn/fmp4j/CoveragePlugin.groovy
diff --git a/buildSrc/src/main/java/dev/sorn/fmp4j/SnakeCaseMethodFormatter.java b/buildSrc/src/main/java/dev/sorn/fmp4j/SnakeCaseMethodFormatter.java
new file mode 100644
index 00000000..ca5432a7
--- /dev/null
+++ b/buildSrc/src/main/java/dev/sorn/fmp4j/SnakeCaseMethodFormatter.java
@@ -0,0 +1,94 @@
+package dev.sorn.fmp4j;
+
+import com.diffplug.spotless.FormatterStep;
+import com.github.javaparser.ParserConfiguration;
+import com.github.javaparser.StaticJavaParser;
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.body.MethodDeclaration;
+import com.github.javaparser.ast.expr.AnnotationExpr;
+import com.github.javaparser.ParserConfiguration.LanguageLevel;
+import java.io.File;
+import java.io.Serial;
+import java.util.List;
+import java.util.regex.Pattern;
+
+
+public class SnakeCaseMethodFormatter implements FormatterStep {
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    // Set of annotations that identify a method as a unit test
+    private static final List<String> TEST_ANNOTATIONS = List.of(
+            "Test",              // JUnit 4 & 5
+            "ParameterizedTest", // JUnit 5
+            "RepeatedTest",      // JUnit 5
+            "TestFactory"        // JUnit 5
+    );
+
+    private static final Pattern SNAKE_CASE_PATTERN = Pattern.compile("^[a-z][a-z0-9_]*$");
+
+    private static final ParserConfiguration parserConfig = new ParserConfiguration()
+            .setLanguageLevel(LanguageLevel.JAVA_17);;
+
+    @Override
+    public String getName() {
+        return "Unit test Naming Enforcement (snake_case)";
+    }
+
+    @Override
+    public String format(String rawUnix, File file) throws Exception {
+        // 1. Parse the source code into an AST
+        StaticJavaParser.setConfiguration(parserConfig);
+        CompilationUnit cu = StaticJavaParser.parse(rawUnix);
+
+        // 2. Walk through all method declarations in the file
+        boolean changed = false;
+        for (MethodDeclaration method : cu.findAll(MethodDeclaration.class)) {
+            if (isUnitTest(method)) {
+                String oldName = method.getNameAsString();
+
+                // 3. Check if the name complies with snake_case
+                if (!SNAKE_CASE_PATTERN.matcher(oldName).matches()) {
+                    String newName = toSnakeCase(oldName);
+                    method.setName(newName);
+                    changed = true;
+                }
+            }
+        }
+
+        // 4. Return the modified source only if changes were made, else return original
+        // (Parsing/printing can sometimes shift whitespace, so we prefer returning original if untouched)
+        return changed ? cu.toString() : rawUnix;
+    }
+
+    /**
+     * Checks if the method is annotated with one of the known test annotations.
+     */
+    private boolean isUnitTest(MethodDeclaration method) {
+        for (AnnotationExpr annotation : method.getAnnotations()) {
+            if (TEST_ANNOTATIONS.contains(annotation.getNameAsString())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Converts a camelCase string to snake_case.
+     * Example: "testUserProfile" -> "test_user_profile"
+     */
+    private String toSnakeCase(String input) {
+        // Regex to look for instances of LowerUpper (e.g. "tU") and insert underscore
+        String regex = "([a-z])([A-Z]+)";
+        String replacement = "$1_$2";
+
+        // Apply replacement and convert to lowercase
+        return input.replaceAll(regex, replacement).toLowerCase();
+    }
+
+    @Override
+    public void close() throws Exception {
+
+    }
+}
+
diff --git a/gradle.properties b/gradle.properties
index 75435c08..a0a9b294 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -8,6 +8,7 @@ apacheCommonsVersion=3.18.0
 apacheHttpComponentsVersion=5.5
 jacksonVersion=2.19.2
 jacksonCsvVersion=2.17.2
+spotlessVersion=7.2.0
 
 # Publishing
 mavenCentralPublishing=true
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
index 249e5832..9bbc975c 100644
Binary files a/gradle/wrapper/gradle-wrapper.jar and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 8fd8efdb..23449a2b 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,7 @@
-#Fri Aug 15 20:38:05 GST 2025
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-9.2.1-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
index 1b6c7873..faf93008 100755
--- a/gradlew
+++ b/gradlew
@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +82,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,22 +133,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,11 +200,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
@@ -205,6 +216,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
 # Use "xargs" to parse quoted args.
 #
 # With -n1 it outputs one arg per line, with the quotes and backslashes removed.
diff --git a/gradlew.bat b/gradlew.bat
index ac1b06f9..9b42019c 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -13,8 +13,10 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 @rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +27,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,13 +43,13 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -56,11 +59,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -75,13 +78,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal
diff --git a/src/test/java/dev/sorn/fmp4j/csv/FmpCsvDeserializerTest.java b/src/test/java/dev/sorn/fmp4j/csv/FmpCsvDeserializerTest.java
index 2090e393..eab9d0a8 100644
--- a/src/test/java/dev/sorn/fmp4j/csv/FmpCsvDeserializerTest.java
+++ b/src/test/java/dev/sorn/fmp4j/csv/FmpCsvDeserializerTest.java
@@ -12,6 +12,7 @@
 import org.junit.jupiter.api.Test;
 
 class FmpCsvDeserializerTest {
+
     private FmpCsvDeserializer deserializer;
 
     @BeforeEach
@@ -29,22 +30,18 @@ void deserialize_array() {
             GOOGL,Alphabet Inc.,2800.50,50
             MSFT,Microsoft Corp.,300.75,75
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(3, result.length);
         assertEquals("AAPL", result[0].symbol());
         assertEquals("Apple Inc.", result[0].name());
         assertEquals(150.25, result[0].price());
         assertEquals(100, result[0].quantity());
-
         assertEquals("GOOGL", result[1].symbol());
         assertEquals("Alphabet Inc.", result[1].name());
         assertEquals(2800.50, result[1].price());
         assertEquals(50, result[1].quantity());
-
         assertEquals("MSFT", result[2].symbol());
         assertEquals("Microsoft Corp.", result[2].name());
         assertEquals(300.75, result[2].price());
@@ -60,17 +57,14 @@ void deserialize_array_with_null_values() {
             AAPL,Apple Inc.,,100
             GOOGL,,2800.50,
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(2, result.length);
         assertEquals("AAPL", result[0].symbol());
         assertEquals("Apple Inc.", result[0].name());
         assertNull(result[0].price());
         assertEquals(100, result[0].quantity());
-
         assertEquals("GOOGL", result[1].symbol());
         assertNull(result[1].name());
         assertEquals(2800.50, result[1].price());
@@ -78,17 +72,15 @@ void deserialize_array_with_null_values() {
     }
 
     @Test
-    void deserialize_array_withByteOrderMark() {
+    void deserialize_array_with_byte_order_mark() {
         // given
         var csv =
                 """
             \uFEFFsymbol,name,price,quantity
             AAPL,Apple Inc.,150.25,100
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(1, result.length);
         assertEquals("AAPL", result[0].symbol());
@@ -103,10 +95,8 @@ void deserialize_array_empty_content() {
         var csv = """
             symbol,name,price,quantity
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(0, result.length);
     }
@@ -119,7 +109,6 @@ void deserialize_array_fails_on_malformed_csv() {
             symbol,name,price,quantity
             AAPL,Apple Inc.,not_a_number,100
             """;
-
         // when // then
         var e = assertThrows(
                 FmpDeserializationException.class,
@@ -140,10 +129,8 @@ void deserialize_array_with_trailing_comma() {
             symbol,name,price,quantity,
             AAPL,Apple Inc.,150.25,100,
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(1, result.length);
         assertEquals("AAPL", result[0].symbol());
@@ -159,10 +146,8 @@ void deserialize_array_with_empty_string_as_null() {
             symbol,name,price,quantity
             AAPL,"",150.25,100
             """;
-
         // when
         var result = deserializer.deserialize(csv, typeRef(TestCsvObject[].class));
-
         // then
         assertEquals(1, result.length);
         assertEquals("AAPL", result[0].symbol());
diff --git a/src/test/java/dev/sorn/fmp4j/json/FmpJsonDeserializerTest.java b/src/test/java/dev/sorn/fmp4j/json/FmpJsonDeserializerTest.java
index 899919cf..510e41ed 100644
--- a/src/test/java/dev/sorn/fmp4j/json/FmpJsonDeserializerTest.java
+++ b/src/test/java/dev/sorn/fmp4j/json/FmpJsonDeserializerTest.java
@@ -12,6 +12,7 @@
 import org.junit.jupiter.api.Test;
 
 class FmpJsonDeserializerTest {
+
     private FmpJsonDeserializer deserializer;
 
     @BeforeEach
@@ -31,10 +32,8 @@ void deserialize_object() {
                 }
             }
             """;
-
         // when
         var obj = deserializer.deserialize(json, typeRef(TestObject.class));
-
         // then
         assertEquals("key", obj.key());
         assertEquals(new TestObjectValue(42), obj.object());
@@ -60,10 +59,8 @@ void deserialize_array() {
                 }
             ]
             """;
-
         // when
         var obj = deserializer.deserialize(json, typeRef(TestObject[].class));
-
         // then
         assertEquals(2, obj.length);
         assertEquals("key3", obj[0].key());
@@ -73,10 +70,9 @@ void deserialize_array() {
     }
 
     @Test
-    void deserialize_object_failsOnMalformedJson() {
+    void deserialize_object_fails_on_malformed_json() {
         // given
         var malformedJson = "{";
-
         // when // then
         var e = assertThrows(
                 FmpDeserializationException.class,
@@ -85,10 +81,9 @@ void deserialize_object_failsOnMalformedJson() {
     }
 
     @Test
-    void deserialize_array_failsOnMalformedJson() {
+    void deserialize_array_fails_on_malformed_json() {
         // given
         var malformedJson = "[";
-
         // when // then
         var e = assertThrows(
                 FmpDeserializationException.class,
@@ -97,7 +92,7 @@ void deserialize_array_failsOnMalformedJson() {
     }
 
     @Test
-    void deserialize_object_failsOnTypeMismatch() {
+    void deserialize_object_fails_on_type_mismatch() {
         // given
         var mismatchedJson =
                 """
@@ -106,7 +101,6 @@ void deserialize_object_failsOnTypeMismatch() {
                 "object": "not_an_object"
             }
             """;
-
         // when // then
         var e = assertThrows(
                 FmpDeserializationException.class,
@@ -123,7 +117,7 @@ void deserialize_object_failsOnTypeMismatch() {
     }
 
     @Test
-    void deserialize_array_failsOnElementTypeMismatch() {
+    void deserialize_array_fails_on_element_type_mismatch() {
         var invalidElementJson =
                 """
             [
@@ -131,7 +125,6 @@ void deserialize_array_failsOnElementTypeMismatch() {
                 {"key": "invalid", "object": "not_an_object"}
             ]
             """;
-
         // when // then
         var e = assertThrows(
                 FmpDeserializationException.class,