Is my Replit app secure?

On most hosts, visitors only ever see your app's public output. On Replit there is an extra surface: the repl itself. If a repl is public, anyone can open it and read your entire source code — every file, including any API key you hard-coded or any .env you committed. This is the most common Replit-specific way secrets leak, and it has nothing to do with how your app behaves.

• Decide deliberately whether your repl should be public or private — and confirm its current setting.

• If the repl is or ever was public, treat any secret that lived in its files as compromised and rotate it.

• Never rely on a repl being 'hard to find' — public means indexable and viewable by anyone.

Replit provides Secrets — a place to store values like API keys and database credentials that are injected into your app as environment variables at runtime. Crucially, Secrets are not part of the repl's shared source, so they don't get exposed when code is viewed or forked.

Do

Put every private key — payment secrets, AI provider keys, database credentials, a Supabase service_role key — in Replit Secrets, and read them only in server-side code.

Don't

Hard-code a key in a source file, paste it into a config you commit, or keep a real .env file in the repl. If you already did, see public .env files and what to do if a secret leaked — rotate the key first, then remove it.

Storing a key in Replit Secrets keeps it out of your source, but it does not make it safe to use anywhere. If your frontend JavaScript reads a secret to call an API directly, that secret is shipped to the browser and becomes public — Secrets or not. Any call that needs a private key must run on your server (your backend route or function), which then talks to the third-party service.

• Identify every call that uses a private key and confirm it runs on the server, not in browser code.

• The frontend should call your own backend; your backend holds the secret and calls the external service.

• Treat anything readable in the browser's network tab or bundle as public.

If your Replit app stores user data, the protection is in your backend, not your screens. Your server code must check that the logged-in user is allowed to read or change each record. If you use Supabase from a Replit app, the same Row Level Security rules apply as anywhere else.

• On every read and write, verify the current user owns or may access the record — don't trust an id from the client.

• Test sign-up, sign-in, sign-out, and password reset, and confirm one user cannot reach another's data.

• Using Supabase: enable RLS on every table with real data and scope each policy.

See the authentication security checklist for the full access boundary, and the Supabase RLS checklist if your data lives in Supabase.

• No secret is hard-coded in source or in a committed .env — all secrets live in Replit Secrets.

• Your repl's visibility (public vs private) is set deliberately and matches what's inside it.

• No backend secret is read in frontend code; privileged calls run on the server.

• Database access checks ownership server-side (or Supabase RLS is enabled and scoped).

• Login, logout, and password reset work, and one user cannot reach another's data.

• You checked the deployed app, not just the editor, and HTTPS is enforced.

• You ran a scan of the deployed URL to catch exposed keys and obvious exposure.

The tool-agnostic master list is the launch security checklist for vibe-coded apps, with browser-protection details in the HTTP security headers checklist.

GuardMint scans your deployed app from the outside and reports what is visible there; the methodology page explains the scope.

• Detects keys and secrets exposed in your deployed frontend, including a service_role key.

• Looks for other leaked secrets and obviously open endpoints on the live site.

• Checks HTTPS, security headers, and other public launch-readiness signals.

Is my Replit app secure by default?

Not automatically. Replit can scaffold a full-stack app quickly, but two things are on you: keeping your repl's source code from being public if it contains anything sensitive, and storing secrets in Replit Secrets rather than in code. A Replit app can run fine while its source — and any key inside it — is publicly visible, so check both before launch.

Does making my repl public expose my code and secrets?

Yes. A public repl shows its full source to anyone, including any secret hard-coded in a file or committed in a .env. That is the most common Replit-specific exposure. Keep secrets in Replit Secrets (which are not part of the shared source), and make sure a repl that contains sensitive logic or data is private.

How should I store secrets in a Replit app?

Use Replit Secrets, which injects values as environment variables your server-side code can read without committing them to the repl's files. Do not hard-code API keys in source, and do not commit a .env file with real values. Remember that a backend secret used in frontend code still becomes public, regardless of where it is stored.

How do I check my Replit app is safe to launch?

Confirm no secret is hard-coded or in a committed file, that secrets live in Replit Secrets, that your repl's visibility is appropriate, that the deployed app (not just the editor) behaves correctly, and that your database access is protected server-side. A free scan of the deployed URL will also flag exposed keys and obvious public exposure.