StackSiren for Vercel
Security check for Vercel apps
Vercel hosts front-end and full-stack apps (often Next.js), including apps generated with v0, Cursor, Bolt or Lovable and deployed from Git. Apps run on a vercel.app subdomain or a custom domain, with preview deployments for each branch or pull request.
Common issues to check before launch
- Secrets exposed through NEXT_PUBLIC_ environment variables, which are bundled into public JavaScript
- No Content-Security-Policy or other security headers configured
- Preview deployments left publicly reachable with production data or keys
Practical fixes
- Only prefix variables with NEXT_PUBLIC_ if they are safe to publish; keep other secrets server-side
- Add security headers in next.config headers() or vercel.json
- Use Vercel Deployment Protection for previews and keep production secrets out of the Preview environment
What StackSiren does
Paste your Vercel app's public URL. StackSiren makes a few normal GET requests and checks for exposed keys, Supabase/Firebase config, security headers, HTTPS, exposed files and SEO basics. The full report includes fix prompts you can paste into Vercel or any AI coding tool.
These are common patterns, not claims about every Vercel app. Many apps have none of these issues.
Related guides
- Exposed API keys in AI-built apps: how to find and fix them
- Supabase 42501 'permission denied for table': RLS explained
- Missing security headers: CSP, HSTS, X-Frame-Options and more
- Exposed .env file, .git folder or VITE_ secret? How to fix it
- Exposed source maps: how to disable them in Vite and Next.js
- CORS misconfiguration: wildcard origins, credentials and fixes