diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
new file mode 100644
index 00000000..b5dba491
--- /dev/null
+++ b/.github/workflows/tests.yaml
@@ -0,0 +1,58 @@
+name: Test all platforms
+
+on: [ pull_request, workflow_dispatch ]
+
+jobs:
+  test:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ ubuntu-latest, macos-13, macos-latest, windows-latest ]
+        python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Linux packages for Qt5/Qt6 support and start Xvfb
+        if: runner.os == 'Linux'
+        uses: pyvista/setup-headless-display-action@v3
+        with:
+          qt: true
+
+      - name: Linux OpenCL support
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y pocl-opencl-icd ocl-icd-opencl-dev gcc clinfo
+          clinfo
+
+      - name : Windows OpenCL support
+        if: runner.os == 'Windows'
+        run: |
+          choco install opencl-intel-cpu-runtime --no-progress --yes
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install setuptools>=40.8.0 wheel pytest
+          python -m pip install .
+          python -m pip freeze --all
+
+      - name: Validate OpenCL
+        if: matrix.os != 'macos-latest'  # no OpenCL device in macOS runners since macos-14
+        run: |
+          python -c "from pytissueoptics.rayscattering.opencl import OPENCL_OK; assert OPENCL_OK"
+
+      - name: Run tests
+        env:
+          PTO_CI_MODE: 1
+        run: |
+          python -m pytest -v
diff --git a/pytissueoptics/rayscattering/opencl/config/CLConfig.py b/pytissueoptics/rayscattering/opencl/config/CLConfig.py
index d4b48e1c..4e3e50a0 100644
--- a/pytissueoptics/rayscattering/opencl/config/CLConfig.py
+++ b/pytissueoptics/rayscattering/opencl/config/CLConfig.py
@@ -178,6 +178,12 @@ def _load(self):
         with open(OPENCL_CONFIG_PATH, "r") as f:
             self._config = json.load(f)
 
+        if os.getenv("PTO_CI_MODE", "0") == "1":
+            warnings.warn("Using default OpenCL configuration for CI mode.")
+            self.DEVICE_INDEX = 0
+            self.N_WORK_UNITS = 128
+            self.MAX_MEMORY_MB = 1024
+
     def _assertExists(self):
         if not os.path.exists(OPENCL_CONFIG_PATH):
             warnings.warn("No OpenCL config file found. Creating a new one.")
diff --git a/pytissueoptics/rayscattering/tests/opencl/config/testCLConfig.py b/pytissueoptics/rayscattering/tests/opencl/config/testCLConfig.py
index e9c3a6ff..e2999338 100644
--- a/pytissueoptics/rayscattering/tests/opencl/config/testCLConfig.py
+++ b/pytissueoptics/rayscattering/tests/opencl/config/testCLConfig.py
@@ -1,6 +1,7 @@
 import os
 import tempfile
 import unittest
+from unittest.mock import patch
 
 from pytissueoptics.rayscattering.opencl import OPENCL_OK
 from pytissueoptics.rayscattering.opencl.config import CLConfig as clc
@@ -25,11 +26,17 @@ def testGivenNoConfigFile_shouldWarnAndCreateANewOne(self):
         self.assertTrue(os.path.exists(clc.OPENCL_CONFIG_PATH))
 
     @tempConfigPath
-    def testGivenNewConfigFile_shouldHaveDefaultValues(self):
+    def testGivenNewConfigFile_shouldHaveDefaultsFromEnvironment(self):
         with self.assertWarns(UserWarning):
             config = clc.CLConfig()
-        self.assertEqual(None, config.N_WORK_UNITS)
-        self.assertEqual(None, config.MAX_MEMORY_MB)
+        if os.getenv("PTO_CI_MODE", "0") == "1":
+            self.assertEqual(0, config.DEVICE_INDEX)
+            self.assertEqual(128, config.N_WORK_UNITS)
+            self.assertEqual(1024, config.MAX_MEMORY_MB)
+        else:
+            self.assertEqual(None, config.DEVICE_INDEX)
+            self.assertEqual(None, config.N_WORK_UNITS)
+            self.assertEqual(None, config.MAX_MEMORY_MB)
         self.assertEqual(1000, config.IPP_TEST_N_PHOTONS)
         self.assertEqual(0.20, config.BATCH_LOAD_FACTOR)
 
@@ -46,7 +53,8 @@ def testGivenMaxMemoryNotSet_whenValidate_shouldWarnAndSetMaxMemory(self):
         with open(clc.OPENCL_CONFIG_PATH, "w") as f:
             f.write('{"DEVICE_INDEX": 0, "N_WORK_UNITS": 100, "MAX_MEMORY_MB": null, '
                     '"IPP_TEST_N_PHOTONS": 1000, "BATCH_LOAD_FACTOR": 0.2}')
-        config = clc.CLConfig()
+        with patch("os.getenv", return_value=None):
+            config = clc.CLConfig()
         with self.assertWarns(UserWarning):
             config.validate()
         self.assertIsNotNone(config.MAX_MEMORY_MB)
@@ -68,8 +76,10 @@ def testGivenFileWithAParameterBelowOrEqualToZero_whenValidate_shouldResetDefaul
         with open(clc.OPENCL_CONFIG_PATH, "w") as f:
             f.write('{"DEVICE_INDEX": 0, "N_WORK_UNITS": 100, "MAX_MEMORY_MB": 0, '
                     '"IPP_TEST_N_PHOTONS": 1000, "BATCH_LOAD_FACTOR": 0.2}')
-        config = clc.CLConfig()
-        with self.assertRaises(ValueError):
-            config.validate()
-        config = clc.CLConfig()
-        self.assertIsNone(config.MAX_MEMORY_MB)
+
+        with patch("os.getenv", return_value=None):
+            config = clc.CLConfig()
+            with self.assertRaises(ValueError):
+                config.validate()
+            config = clc.CLConfig()
+            self.assertIsNone(config.MAX_MEMORY_MB)