diff --git a/.circleci/config.yml b/.circleci/config.yml
index a88d1068baa1d..977a27b5b5cb2 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -954,6 +954,44 @@ jobs:
       - run-tests-chrome:
           title: "browser64_4gb"
           test_targets: "browser64_4gb"
+  test-browser-firefox:
+    executor: focal
+    steps:
+      - prepare-for-tests
+      - run-tests-firefox:
+          title: "browser"
+          # browser.test_sdl2_mouse and/or SDL2 should be fixed. The case happens
+          # to be failing here, and the root cause might be related with the
+          # initial position of the mouse pointer relative to the canvas.
+          # browser.test_html5_webgl_create_context is skipped because
+          # anti-aliasing is not well supported.
+          # browser.test_webgl_offscreen_canvas_in_pthread and
+          # browser.test_webgl_offscreen_canvas_in_mainthread_after_pthread
+          # are crashing Firefox (bugzil.la/1281796). The former case is
+          # further blocked by issue #6897.
+          test_targets: "
+            browser
+            skip:browser.test_sdl2_mouse
+            skip:browser.test_html5_webgl_create_context
+            skip:browser.test_webgl_offscreen_canvas_in_pthread
+            skip:browser.test_webgl_offscreen_canvas_in_mainthread_after_pthread
+            skip:browser.test_glut_glutget
+            "
+  test-browser-firefox-wasm64:
+    executor: focal
+    steps:
+      - checkout
+      - run:
+          name: submodule update
+          command: git submodule update --init
+      - pip-install
+      - install-emsdk
+      - run-tests-firefox:
+          title: "browser64"
+          test_targets: "
+            browser64.test_sdl_image
+            browser64.test_dylink_many
+            "
   # TODO(sbc): Re-enable once we figure out why the emrun tests are
   # locking up.
   #test-browser-chrome-emrun:
@@ -965,6 +1003,72 @@ jobs:
     executor: focal
     steps:
       - test-sockets-chrome
+  # windows and mac do not have separate build and test jobs, as they only run
+  # a limited set of tests; it is simpler and faster to do it all in one job.
+  test-windows:
+    working_directory: "~/path with spaces"
+    executor:
+      name: win/server-2019
+      shell: bash.exe -eo pipefail
+    environment:
+      PYTHONUNBUFFERED: "1"
+      EMSDK_NOTTY: "1"
+      # clang can compile but not link in the current setup, see
+      # https://github.com/emscripten-core/emscripten/pull/11382#pullrequestreview-428902638
+      EMTEST_LACKS_NATIVE_CLANG: "1"
+      EMTEST_SKIP_V8: "1"
+      EMTEST_SKIP_EH: "1"
+      EMTEST_SKIP_WASM64: "1"
+      EMTEST_SKIP_SCONS: "1"
+      EMTEST_SKIP_RUST: "1"
+      EMTEST_SKIP_NODE_CANARY: "1"
+      EMTEST_BROWSER: "0"
+    steps:
+      - checkout
+      - run:
+          name: Install packages
+          command: |
+            choco install -y cmake.portable ninja pkgconfiglite
+      - run:
+          name: Add python to bash path
+          command: echo "export PATH=\"$PATH:/c/Python27amd64/\"" >> $BASH_ENV
+      # note we do *not* build all libraries and freeze the cache; as we run
+      # only limited tests here, it's more efficient to build on demand
+      - install-emsdk
+      - pip-install:
+          python: "$EMSDK_PYTHON"
+      - run-tests:
+          title: "crossplatform tests"
+          test_targets: "--crossplatform-only"
+      - upload-test-results
+      # Run a single websockify-based test to ensure it works on windows.
+      - run-tests:
+          title: "sockets.test_nodejs_sockets_echo*"
+          test_targets: "sockets.test_nodejs_sockets_echo*"
+      - upload-test-results
+
+  test-mac-arm64:
+    executor: mac-arm64
+    environment:
+      # We don't install d8 or modern node on the mac runner so we skip any
+      # tests that depend on those.
+      EMTEST_SKIP_V8: "1"
+      EMTEST_SKIP_EH: "1"
+      EMTEST_SKIP_WASM64: "1"
+      EMTEST_SKIP_SCONS: "1"
+      EMTEST_SKIP_RUST: "1"
+      # Some native clang tests assume x86 clang (e.g. -sse2)
+      EMTEST_LACKS_NATIVE_CLANG: "1"
+      EMCC_SKIP_SANITY_CHECK: "1"
+    steps:
+      - setup-macos
+      - install-emsdk
+      # TODO: We can't currently do pip install here since numpy and other packages
+      # are currently missing arm64 macos binaries.
+      - run-tests:
+          title: "crossplatform tests"
+          test_targets: "--crossplatform-only"
+      - upload-test-results
 
 workflows:
   build-test:
@@ -1010,9 +1114,15 @@ workflows:
       - test-browser-chrome-wasm64-4gb:
           requires:
             - build-linux
+      - test-browser-firefox:
+          requires:
+            - build-linux
+      - test-browser-firefox-wasm64
       - test-sockets-chrome:
           requires:
             - build-linux
       - test-jsc
       - test-spidermonkey
       - test-node-compat
+      - test-windows
+      - test-mac-arm64