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Hardening an App Built with Replit Agent

Updated 2026-10-17

Replit Agent can scaffold a full-stack app with a database. Before launch, review the parts that determine who can do what.

Backend

Confirm every API route checks the session and ownership, that database queries are parameterized, and that secrets are read from Replit Secrets only on the server.

Frontend and serving

Serve the built frontend directory only, add security headers in your server (e.g. helmet for Express), and verify dotfiles return 404.

import helmet from "helmet";
app.use(helmet());

Checklist

  • Secrets in Replit Secrets
  • Parameterized queries
  • Auth + ownership checks
  • helmet or equivalent headers
  • Static root = build folder

Copy-paste fix prompt

Harden this Replit app: add helmet (or equivalent) security headers, make sure static serving only exposes the build folder, parameterize all SQL, and add session + ownership checks to every API route.

FAQ

Is the built-in database private?

It is reachable by your backend; what your API exposes is what matters. Check every route.

Do I need a custom domain?

Not for security, but you need HTTPS everywhere and headers on whatever domain you share.

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