diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d6e2225..d2ecaba 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.12'
         cache: 'pip'
@@ -40,10 +40,10 @@ jobs:
         os: [ubuntu-latest, windows-latest, macos-latest]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: ${{ matrix.python-version }}
         cache: 'pip'
@@ -56,7 +56,7 @@ jobs:
       run: python -m pytest tests/unit/ -v --cov=nutrient_dws --cov-report=xml --cov-report=term
 
     - name: Upload coverage to Codecov
-      uses: codecov/codecov-action@v4
+      uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4
       if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.12'
       with:
         files: ./coverage.xml
@@ -68,10 +68,10 @@ jobs:
     needs: [lint-and-type-check, unit-tests]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.12'
         cache: 'pip'
diff --git a/.github/workflows/integration-tests.yml b/.github/workflows/integration-tests.yml
index 15fd475..49d5b79 100644
--- a/.github/workflows/integration-tests.yml
+++ b/.github/workflows/integration-tests.yml
@@ -16,10 +16,10 @@ jobs:
         python-version: ['3.10', '3.11', '3.12']
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: ${{ matrix.python-version }}
         cache: 'pip'
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 9c770be..b9e3201 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -16,10 +16,10 @@ jobs:
 
     steps:
     # Use current branch/tag
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.10'
 
@@ -32,4 +32,4 @@ jobs:
       run: python -m build
 
     - name: Publish to PyPI
-      uses: pypa/gh-action-pypi-publish@release/v1
+      uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
diff --git a/.github/workflows/scheduled-integration-tests.yml b/.github/workflows/scheduled-integration-tests.yml
index cd6e679..49a9725 100644
--- a/.github/workflows/scheduled-integration-tests.yml
+++ b/.github/workflows/scheduled-integration-tests.yml
@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.12'
         cache: 'pip'
@@ -74,7 +74,7 @@ jobs:
 
     - name: Create issue if tests fail
       if: failure() && steps.test-run.outcome == 'failure'
-      uses: actions/github-script@v7
+      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7
       with:
         script: |
           const date = new Date().toISOString().split('T')[0];
@@ -115,7 +115,7 @@ jobs:
           }
 
     - name: Upload test artifacts
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
       if: always()
       with:
         name: scheduled-integration-results-${{ github.run_number }}
@@ -126,7 +126,7 @@ jobs:
 
     - name: Notify on success after previous failure
       if: success() && steps.test-run.outcome == 'success'
-      uses: actions/github-script@v7
+      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7
       with:
         script: |
           // Close any open integration failure issues
diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index a47e70d..29f4d32 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -16,12 +16,12 @@ jobs:
       security-events: write
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
       with:
         fetch-depth: 0
 
     - name: Run Gitleaks
-      uses: gitleaks/gitleaks-action@v2
+      uses: gitleaks/gitleaks-action@ff98106e4c7b2bc287b24eaf42907196329070c7 # v2
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         GITLEAKS_LICENSE: ${{ secrets.GITLEAKS_LICENSE }}
@@ -55,10 +55,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.12'
         cache: 'pip'
@@ -89,7 +89,7 @@ jobs:
       continue-on-error: true
 
     - name: Upload security scan results
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
       if: always()
       with:
         name: security-reports-${{ github.run_number }}
@@ -109,10 +109,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: '3.12'
         cache: 'pip'