How to check if your web app is secure

Start with the surface anyone on the internet can see. A scan should check for the common mistakes that are easy to ship by accident and easy for an attacker to find.

• No private secrets are visible in the frontend bundle.

• No .env, .git, config, source map, or backup files are publicly reachable.

• HTTPS works with a valid certificate and sane redirects.

• Security headers are present or intentionally configured.

• Robots.txt and sitemap.xml do not expose private app surfaces.

• Admin, debug, staging, and internal routes are not publicly open.

You can run this first pass with a free website security scan.

Security bugs often hide behind a working UI. The page might hide a button, but the API or database may still allow the action.

• Create two test users and confirm each can only see their own data.

• Change ids in URLs or requests and confirm cross-user access is blocked.

• Try admin-only actions as a normal user and confirm the server rejects them.

• Test logout, password reset, expired sessions, and invite flows.

• Review database policies for every table that holds user or customer data.

If you use Supabase, make the Supabase RLS checklist part of this step. For login and session behavior, use the authentication security checklist.

A finding is only useful once you know how much it matters. Sort what you found by what an outsider could actually do with it, not by how alarming the label sounds.

Serious findings

Exposed private keys, public sensitive files, open database access, broken authorization, and unverified payment webhooks are the findings worth stopping for. Each one means someone other than you can already reach something they should not.

Fix next

Missing hardening headers, weaker CSP, incomplete monitoring, and cleanup tasks still matter, but they are usually secondary to direct exposure or access control failures. Use the HTTP security headers checklist to handle browser protections clearly.

You have finished the assessment — as opposed to run out of patience — when you can state each of these from something you actually observed, not from what the code appears to do:

• A fresh scan of the live URL has no exposed secrets or public sensitive files.

• Every table or collection with private data has scoped access rules.

• Normal users cannot perform admin or owner-only actions.

• Payments, webhooks, and plan permissions are verified server-side.

• The app has HTTPS, basic security headers, and intentional robots/sitemap behavior.

• You know which risks remain and whether they require a deeper audit.

That result tells you where the app stands today. Turning it into a ship-or-wait call is a separate step: the launch security checklist is the sequenced pass to run on the day, and the AI app launch readiness guide covers the non-security half of that decision — production configuration, monitoring, and whether you can roll back when something breaks.

How do I check if my web app is secure?

Check your web app in two passes. First, run an external scan of the live URL for exposed secrets, public files, HTTPS issues, missing security headers, and obvious risky routes. Second, manually test auth, authorization, database access, admin actions, payment flows, and any sensitive business logic. Fix high-severity exposure first, then rescan.

How is testing my app different from following a security checklist?

A checklist tells you which areas to review; testing tells you what your app actually does. Reading your code and concluding that users can only see their own rows is a guess. Signing in as a second account, changing an ID in the request, and watching the server refuse it is evidence. Use a checklist to make sure you covered every area, and testing to confirm each one behaves the way you think it does.

Can I check web app security without being a security expert?

You can catch many common launch issues without being a security expert by using a clear external scan and a practical manual checklist. You may still need a qualified developer or security reviewer for complex authorization, regulated data, payments, enterprise access, or high-risk workflows.

Should I scan before or after fixing security issues?

Both. Scan before fixing to find the visible issues, then scan again after changes to confirm the live app no longer exposes them. A local code change does not count as fixed until the deployed site is clean.