Launch Ready API security Checklist for AI-built SaaS app: Ready for security review in marketplace products?.

What "ready" means for an AI-built SaaS app in a marketplace review

For a marketplace product, "ready" does not mean the app merely works on your laptop or passes a happy-path demo. It means the product can survive a security review, handle real users, and not create support debt the moment traffic arrives.

I would call an AI-built SaaS app ready when these are true:

• No exposed secrets in code, logs, or frontend bundles.
• Authentication and authorization are enforced on every API route, with no obvious bypasses.
• Production uses real domains, SSL, redirects, and email authentication that pass SPF, DKIM, and DMARC.
• Error handling does not leak stack traces, tokens, or internal IDs.
• Monitoring is live so you know when something breaks before customers do.
• The deployment is repeatable enough that a reviewer can trust it and a customer can use it.

If you cannot say "yes" to those points, you are not ready for a marketplace security review yet. You are still in prototype territory.

That is the difference between "it runs" and "it can be reviewed."

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Auth on every API route | No unauthenticated access to private data or actions | Reviewers test direct API calls, not just UI flows | Data exposure, account takeover | | Authorization by tenant/user | Users only access their own records | AI-built apps often miss object-level checks | Cross-tenant data leaks | | Secrets handling | Zero secrets in frontend or public repo | Exposed keys get abused fast | Cloud bills spike, data gets stolen | | Input validation | Server rejects malformed and dangerous payloads | AI-generated code often trusts client input too much | Injection bugs, crashes | | Rate limiting | Abuse paths are throttled per IP/user/token | Marketplace traffic includes bots and retries | Cost blowouts, denial of service | | CORS policy | Only approved origins can call browser APIs | Loose CORS creates cross-site abuse risk | Token theft, unauthorized requests | | Error handling | No stack traces or internal details in responses | Reviewers look for information leakage | Attackers learn your internals | | Logging hygiene | Logs exclude passwords, tokens, PII where possible | Logs become a second data store if ignored | Compliance problems, incident response pain | | TLS and domain setup | HTTPS enforced with clean redirects and valid certs | Reviewers expect production-grade delivery | Broken trust signals, failed review | | Email auth + monitoring | SPF/DKIM/DMARC pass and uptime alerts are active | Marketplace ops teams check deliverability and reliability too | Emails land in spam, outages go unnoticed |

A good threshold for this stage: zero exposed secrets, no critical auth bypasses, and p95 API latency under 500 ms for core endpoints.

The Checks I Would Run First

1. Verify authentication on every private endpoint

Signal: If I can hit a private endpoint without a valid session or token, the app is not ready.

Tool or method: I test with curl/Postman plus browser dev tools. I also inspect network calls from the frontend to see whether the UI is doing security work that should live on the server.

Fix path: Move auth checks into middleware or route handlers. Do not rely on hidden buttons or client-side guards. If this is an AI-built app from Lovable, Bolt, Cursor, or v0 codegen output, I assume at least one endpoint was left open until proven otherwise.

2. Check object-level authorization

Signal: A logged-in user can fetch another user's record by changing an ID in the URL or request body.

Tool or method: I try ID swapping on users, orders, projects, invoices, files, and org records. This is one of the fastest ways to find marketplace-blocking flaws.

Fix path: Enforce tenant_id and owner_id checks server-side on every read/write/delete action. If you use row-level security in Postgres or policy-based access control elsewhere, I verify it against real routes instead of trusting the schema alone.

3. Scan for exposed secrets

Signal: Any API key appears in source code, frontend bundles, build logs, CI output, browser storage snapshots, or public env files.

Tool or method: I run secret scanning across repo history and production artifacts. I also inspect deployed JS bundles because AI-built apps often ship values that were meant to stay server-side.

Fix path: Rotate any exposed key immediately. Move sensitive values to environment variables on the server only. Add pre-commit scanning so this does not recur.

A minimal pattern looks like this:

## Example: keep secrets server-side only
API_KEY=your_key_here
NEXT_PUBLIC_API_KEY=

The rule is simple: if the browser needs it to function as a user-facing value like a public analytics ID maybe fine; if it grants access to data or infrastructure access then it must never reach the client.

4. Test input validation and error handling

Signal: Bad payloads cause 500 errors with stack traces instead of clean validation failures.

Tool or method: I send empty strings, oversized payloads, unexpected types, SQL-like strings where relevant, broken JSON objects, and missing required fields. Then I inspect whether responses fail safely with clear 4xx messages.

Fix path: Validate on the server using explicit schemas. Return stable error shapes. Do not echo raw exceptions back to clients. For marketplace review readiness I want validation failures to be predictable enough that support load stays low after launch.

5. Review CORS and browser-accessible surfaces

Signal: Any origin can call sensitive endpoints from a browser context.

Tool or method: I inspect CORS headers with dev tools and test requests from an unapproved origin. I also check whether cookies are set securely with SameSite behavior appropriate to your auth model.

Fix path: Lock CORS down to known production domains only. If you have subdomains for app.example.com and api.example.com then configure them intentionally instead of using wildcards because "it worked" is not a security strategy.

6. Confirm logging does not leak private data

Signal: Logs contain passwords reset tokens session IDs payment details personal data or full request bodies without redaction.

Tool or method: I review application logs error logs reverse proxy logs cloud logs and any third-party observability tools. I search for token-like patterns as well as obvious PII fields.

Fix path: Redact sensitive fields at source. Keep enough context for debugging but not enough for abuse. In practice that means structured logs with request IDs user IDs where appropriate timestamps status codes and short error codes rather than raw payload dumps.

Red Flags That Need a Senior Engineer

If you see any of these patterns you should stop DIYing and buy help:

1. You have no idea where secrets live.

• That usually means they have already leaked into code history or frontend artifacts somewhere.

2. Your app uses AI-generated backend routes without tests.

• Marketplace reviewers will find edge cases faster than your QA process will.

3. Authentication exists in the UI but not consistently on the API.

• This is how private data escapes even when screens look locked down.

4. You changed hosting three times already.

• Every migration adds DNS risk SSL risk redirect risk and downtime risk if nobody owns the handover properly.

5. You cannot explain your tenant model in one sentence.

• If you cannot describe who can see what then your authorization layer probably has gaps.

These are exactly the failure modes that turn into launch delays support tickets refund requests and embarrassing review feedback from platform partners.

DIY Fixes You Can Do Today

1. Rotate anything suspicious now.

• If a key was ever committed publicly assume it is compromised until rotated.

2. Turn on MFA everywhere.

• GitHub cloud provider email registrar DNS provider all of it.

3. Set production-only environment variables.

• Remove hardcoded values from frontend code immediately.

4. Tighten your domain setup.

• Force HTTPS add redirects from non-www to www or vice versa choose one canonical host and stick to it.

5. Add basic monitoring today.

• At minimum set uptime alerts for homepage login flow API health endpoint and email deliverability signals if your app sends mail.

If you want one practical benchmark before asking for review: make sure core pages load under 2.5 seconds LCP on mobile-equivalent conditions and core APIs return under p95 500 ms under normal load. Slow products get scrutinized harder because slowness often hides broken architecture underneath it.

Where Cyprian Takes Over

Here is how checklist failures map to Launch Ready deliverables:

| Failure found during audit | Launch Ready deliverable | |---|---| | Missing domain setup or broken redirects | DNS configuration plus canonical redirects | | SSL warnings mixed content insecure hostnames | Cloudflare setup plus SSL enforcement | | Exposed secrets hardcoded env confusion | Production environment variables plus secrets cleanup guidance | | No uptime visibility blind deployments | Uptime monitoring setup plus alert handover | | Email lands in spam fails sender checks | SPF DKIM DMARC configuration | | Unclear deployment state staging prod mismatch | Production deployment verification | | Weak caching slow pages noisy traffic spikes | Cloudflare caching tuning | | Risky public exposure during launch window | DDoS protection via Cloudflare |

My delivery window is 48 hours because this work should be treated like launch infrastructure surgery rather than open-ended consulting. The goal is simple: make the product safe enough to submit for review without creating another week of firefighting afterward.

What I would typically hand over at the end:

• Domain connected correctly
• Email authentication passing
• SSL active everywhere
• Production deployment verified
• Secrets removed from risky places
• Monitoring live
• Handover checklist with next-step risks called out plainly

References

• https://roadmap.sh/api-security-best-practices
• https://roadmap.sh/cyber-security
• https://roadmap.sh/code-review-best-practices
• https://roadmap.sh/qa
• https://developers.cloudflare.com/ssl/edge-certificates/

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Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*