diff --git a/.github/workflows/cross-language-integration.yml b/.github/workflows/cross-language-integration.yml
index 9ba2a2d7b..495692e77 100644
--- a/.github/workflows/cross-language-integration.yml
+++ b/.github/workflows/cross-language-integration.yml
@@ -22,6 +22,14 @@ jobs:
         with:
           go-version: '1.25'
 
+      - name: Cache npm downloads
+        uses: actions/cache@v6
+        with:
+          path: ~/.npm
+          key: npm-cross-language-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
+          restore-keys: |
+            npm-cross-language-${{ runner.os }}-
+
       - name: Install dependencies
         run: npm install
 
diff --git a/.github/workflows/validation.yaml b/.github/workflows/validation.yaml
index 7bb00098e..3c635dc0f 100644
--- a/.github/workflows/validation.yaml
+++ b/.github/workflows/validation.yaml
@@ -28,6 +28,20 @@ jobs:
         with:
           python-version: '3.11'
 
+      - name: Resolve npm cache directory
+        id: npm-cache-dir
+        shell: bash
+        # tr strips the carriage return npm emits on the Windows runner.
+        run: echo "dir=$(npm config get cache | tr -d '\r')" >> "$GITHUB_OUTPUT"
+
+      - name: Cache npm downloads
+        uses: actions/cache@v6
+        with:
+          path: ${{ steps.npm-cache-dir.outputs.dir }}
+          key: npm-validation-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
+          restore-keys: |
+            npm-validation-${{ runner.os }}-
+
       - name: Install dependencies
         run: npm install