Is my Replit app secure? How do I test it?
You can only tell by testing the deployed app. Check that no secret from the Secrets pane is read by browser code, that your database does not answer the public without a login, and that every endpoint checks who is calling and whether they own the record. The free ArgosX scan checks exposed secrets and database exposure on your live URL with no signup; a Pro scan signs in as two of your test accounts to test cross-user access.
Security scan for Replit apps
Replit Agent builds and deploys a full app in one place, which makes it easy to ship before the security layer is finished. The Secrets pane keeps keys out of your source, but a secret still leaks if client-side code reads it, and endpoints the Agent wrote to make a feature work often skip the ownership check. We scan the app you deployed, from the outside, the way a stranger would reach it.
Runs on your deployed URL in minutes. No signup, no card, and it never logs in: public surface only.
What Replit apps typically get wrong
Replit Secrets keeps a key out of your repo, but if browser code reads it, the value is sent to every visitor's browser. Secrets belong in server-side code only.
If the Agent wired the app to Supabase or another Postgres and queries it with a key in the page, a table without a row policy is readable by anyone.
The Agent writes endpoints to make features work. Each one needs a login check and an ownership check, or anyone can call it directly and fetch other users' records.
What the scan checks on your live app
We look for real private keys in the pages and bundles your deployed app sends to visitors, and tell them apart from publishable keys that are meant to be public.
If your live app talks to Supabase from the browser, we use the key it already serves and check what that key can read without a login, table by table.
CSP, HSTS, frame protection and the other one-line fixes fast deploys skip.
On a Pro scan, with your permission and test accounts you provide, we sign in as two users and check whether one can read or change the other's data through your endpoints, with the exact request and response as proof.
Being straight about scope: the free scan sees only what an anonymous visitor sees. Signed-in cross-user testing is a paid scan, needs your explicit permission and test accounts you provide, and takes tens of minutes because we actually drive the app. Plans on pricing.
Does Replit check this for you?
Use whatever security checks your Replit plan offers, and ask the Agent to review its own auth and data access. What an independent scan adds: it is not the builder grading its own work, it tests the app you deployed rather than the code as written, and on a Pro scan it signs in as two real users to prove whether your endpoints actually keep their data apart.
Common questions
The free scan only touches your public surface: the pages and endpoints any anonymous visitor can already reach. It does not log in, create accounts or write data. Signed-in testing only happens on a paid scan, with your explicit permission and test accounts you provide.
It keeps them out of your source code, which is good, but it does not make a key safe to use in the browser. If client-side code reads a secret, its value is sent to every visitor. Use secrets only in server-side code. The free scan flags a real private key if it finds one served to the browser.
Prefer the checklist first? See the Replit pre-launch checklist.
Platform behavior described as of September 2026. Platforms change their defaults; the scan tests what your app actually does today.