Launch Ready API security Checklist for AI-built SaaS app: Ready for app 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 works on my laptop." It means the reviewer can sign up, verify email, log in, complete the core workflow, and not hit broken auth, missing env vars, insecure endpoints, or random 500s.

For an AI-built SaaS app, I would call it ready only if these are true:

• No exposed secrets in code, logs, or client bundles.
• Auth is enforced on every private API route.
• p95 API latency is under 500ms for the main user flow.
• Email deliverability is working with SPF, DKIM, and DMARC passing.
• SSL is valid everywhere, including subdomains and redirects.
• The deployment is stable enough that a reviewer will not see downtime during the review window.
• Monitoring is live so you know about failures before the reviewer does.

If any of those fail, you are not "app review ready." You are just hoping the reviewer does not find the weak point first.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Auth on all private APIs | Every protected route rejects unauthenticated requests | Prevents data exposure and account abuse | Reviewer sees other users' data or gets blocked mid-flow | | Authorization by user/org | Users can only access their own records | Stops cross-account leaks | Marketplace rejection and security incident | | Secrets handling | Zero secrets in client code, repo history, or logs | Prevents key theft and account takeover | Stripe, OpenAI, email, or DB compromise | | Email setup | SPF, DKIM, DMARC all pass | Ensures verification and transactional emails land | Signup fails or emails hit spam | | SSL everywhere | No mixed content; all domains/subdomains use HTTPS | Required for trust and browser compatibility | Login errors and review friction | | Redirects and canonical domain | One clean domain path with 301 redirects | Prevents duplicate URLs and broken callbacks | OAuth and email links fail | | Rate limiting | Sensitive endpoints have rate limits and abuse protection | Reduces bot abuse and brute force risk | Cost spikes and login attacks | | Input validation | All API inputs are validated server-side | Blocks malformed payloads and injection paths | 500s, corrupted data, exploit paths | | Observability | Uptime monitoring plus error logging enabled | Lets you detect issues fast during review | Silent failures and slow support response | | Performance baseline | Main flow loads fast; p95 API under 500ms; LCP under 2.5s where applicable | Reviewers judge polish as much as function | Drop-off during signup and demo |

The Checks I Would Run First

1. Auth bypass check

• Signal: I can call a private endpoint without a valid session or token.
• Tool or method: Manual cURL/Postman test against every route used in onboarding, billing, profile, and data access.
• Fix path: Add middleware at the route layer first. Then add integration tests that fail if any protected endpoint returns 200 without auth.

2. Authorization scope check

• Signal: A logged-in user can request another user's record by changing an ID in the URL or body.
• Tool or method: Test ID swapping across org IDs, project IDs, workspace IDs, and invoice IDs.
• Fix path: Enforce ownership checks server-side using user ID plus org membership. Do not trust client-side filtering.

3. Secret exposure check

• Signal: API keys appear in frontend bundles, environment dumps, Git history, logs, analytics events, or error traces.
• Tool or method: Search repo history plus deployed assets. Check browser dev tools network payloads and source maps.
• Fix path: Rotate anything exposed immediately. Move secrets to server-only env vars and remove source maps from public builds.

4. Email deliverability check

• Signal: Verification emails never arrive or land in spam.
• Tool or method: Validate DNS records with MXToolbox or your registrar panel. Send test mail to Gmail and Outlook.
• Fix path: Set SPF/DKIM/DMARC correctly. Use one sending domain. Add proper From/Reply-To alignment.

5. Error handling check

• Signal: Failed API calls return raw stack traces or vague 500 errors with no request ID.
• Tool or method: Trigger invalid payloads, expired tokens, duplicate submissions, timeouts, and quota limits.
• Fix path: Return safe error messages with stable codes. Log internal details privately with request IDs for support.

6. Deployment stability check

• Signal: A fresh deploy breaks login callbacks, webhooks, CORS behavior, or environment-specific config.
• Tool or method: Run a staging-to-production parity test after deploy. Verify DNS propagation and SSL status.
• Fix path: Lock config into environment variables per stage. Add smoke tests for login, signup, webhook receipt, and main dashboard load.

Red Flags That Need a Senior Engineer

1. You have no idea where secrets live If you are unsure whether keys are in frontend code, old commits, CI logs, or preview deployments, stop guessing. One exposed key can create downtime faster than any feature bug.

2. The app uses AI-generated routes without route-level auth AI tools often produce working flows that forget enforcement on the server side. That is how you end up with "it looked secure" but the reviewer can still query private data.

3. OAuth or email verification is flaky If signup depends on redirect URLs matching exactly across domains and subdomains but your DNS is messy, this becomes a launch blocker. These failures waste review cycles because they look like product bugs when they are really infrastructure bugs.

4. You have no monitoring on production If there is no uptime alerting plus error tracking plus basic logs with request IDs, you will discover problems from users instead of dashboards. That drives support load up immediately after launch.

5. The app passes locally but fails after deployment This usually means environment mismatch: wrong env vars, missing Cloudflare rules, stale build cache artifacts, bad CORS config, or hidden dependency issues. At that point DIY becomes expensive because every fix risks breaking something else.

DIY Fixes You Can Do Today

1. List every secret Make a spreadsheet of all API keys, tokens,, SMTP creds,, DB URLs,, webhook secrets,, OAuth client secrets,,and admin passwords. Rotate anything that has ever been shared outside your laptop.

2. Check public exposure Open your deployed site in an incognito browser and inspect page source plus network calls. If you see keys in JS bundles,, source maps,,or responses,,remove them before review day.

3. Test your login flow from scratch Create a new account using a clean browser profile,, then verify email,, log out,, log back in,,and open each protected page directly by URL. If any step breaks,,you have a production blocker.

4. Validate DNS records Confirm your root domain,, www redirect,, subdomains,, SPF,, DKIM,, DMARC,,and SSL status from the registrar panel plus Cloudflare dashboard. Bad DNS causes more launch pain than most founders expect.

5. Add basic uptime monitoring Use one simple monitor on homepage,,,login,,,and one private API health endpoint., Set alerts to email plus Slack., If those pages fail for more than 5 minutes,,,you want to know immediately.

A minimal SPF example looks like this:

v=spf1 include:_spf.google.com include:sendgrid.net ~all

That is not enough by itself., but it is better than shipping without any mail authentication at all.

Where Cyprian Takes Over

Here is how I map failures to the service deliverables:

• Domain issues -> domain setup,,,,www/root redirects,,,,subdomain routing,,,,canonical URL cleanup
• Email issues -> SPF,,,,DKIM,,,,DMARC,,,,sending domain alignment,,,,transactional email verification
• SSL issues -> Cloudflare setup,,,,certificate validation,,,,HTTPS enforcement
• Deployment issues -> production deployment,,,,environment variables,,,,build fixes,,,,rollback-safe release
• Secret issues -> secret cleanup,,,,server-only config,,,,rotation guidance
• Performance/reliability issues -> caching,,,,DDoS protection,,,,uptime monitoring
• Handover risk -> checklist handover so you know what was changed and what to watch next

My recommendation is simple: if you are within 72 hours of marketplace submission and you have even one unresolved item in auth,,,email deliverability,,,or deployment stability,,,do not try to patch everything yourself., Buy the sprint., Ship cleanly., Then move on to conversion optimization instead of firefighting infrastructure.

References

• roadmap.sh API Security Best Practices: https://roadmap.sh/api-security-best-practices
• roadmap.sh Cyber Security Roadmap: https://roadmap.sh/cyber-security
• roadmap.sh Code Review Best Practices: https://roadmap.sh/code-review-best-practices
• OWASP API Security Top 10: https://owasp.org/www-project-api-security/
• Cloudflare SSL/TLS documentation: https://developers.cloudflare.com/ssl/

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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.*