diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..8b1561e
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,89 @@
+name: Build Extension Packages
+
+on:
+  push:
+    branches: [main]
+    paths-ignore:
+      - "README.md"
+      - "LICENSE"
+  pull_request:
+    branches: [main]
+    paths-ignore:
+      - "README.md"
+      - "LICENSE"
+  workflow_dispatch: # Allows manual re-run from GitHub UI
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: "npm"
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build extension packages
+        run: npm run build
+
+      - name: Upload Chrome extension artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: carbon-visualizer-chrome
+          path: build/carbon-visualizer-chrome.zip
+          retention-days: 30
+
+      - name: Upload Firefox extension artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: carbon-visualizer-firefox
+          path: build/carbon-visualizer-firefox.zip
+          retention-days: 30
+
+      - name: Comment PR with artifact links
+        if: github.event_name == 'pull_request'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const { data: comments } = await github.rest.issues.listComments({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.issue.number,
+            });
+
+            const botComment = comments.find(comment =>
+                comment.user.type === 'Bot' &&
+                comment.body.includes('📦 Extension packages built successfully!')
+            );
+
+            const commentBody = `📦 Extension packages built successfully!
+
+            **[Download your Chrome and Firefox extension packages](https://github.com/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId})**`;
+
+            if (botComment) {
+                await github.rest.issues.updateComment({
+                    owner: context.repo.owner,
+                    repo: context.repo.repo,
+                    comment_id: botComment.id,
+                    body: commentBody
+                });
+            } else {
+                await github.rest.issues.createComment({
+                    owner: context.repo.owner,
+                    repo: context.repo.repo,
+                    issue_number: context.issue.number,
+                    body: commentBody
+                });
+            }
+
+      - name: Notify on failure
+        if: failure()
+        run: |
+          echo "❌ Build failed! Check the logs above for details."