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

Launch Ready API Security Checklist for AI-built SaaS app: Ready for launch in marketplace products?

If I say an AI-built SaaS app is "ready" for launch in a marketplace product, I mean this: a stranger can sign up, authenticate, use the core API flows, pay if needed, and not expose data, break billing, or trigger support tickets within the first 24 hours.

For a marketplace launch, "ready" also means the app survives real traffic patterns and review scrutiny. That includes no exposed secrets, no auth bypasses, no broken redirects, no email deliverability issues, no missing SSL, no weak CORS rules, and no monitoring gap that leaves you blind when something fails.

A founder should be able to self-assess with one simple question: if 100 users arrive from a marketplace listing tomorrow, will the product stay up, keep data private, and let users complete the main journey without manual intervention?

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Authentication | No anonymous access to protected APIs | Stops account takeover and data leaks | Users can view or change other accounts | | Authorization | Every request is scoped by tenant/user ID | Prevents cross-customer data exposure | One customer sees another customer's records | | Secrets handling | Zero secrets in code, logs, or client bundles | Protects API keys and database access | Breach risk and emergency key rotation | | Input validation | All API inputs are validated server-side | Blocks injection and malformed requests | Crashes, bad writes, and security bugs | | Rate limiting | Sensitive endpoints have limits per IP/user | Reduces abuse and cost spikes | Bot traffic drains your API budget | | CORS policy | Only approved origins can call browser APIs | Prevents unwanted cross-site access | Data exposure from rogue web apps | | TLS/SSL | HTTPS only with valid certs on all domains/subdomains | Protects login and token traffic | Browser warnings and failed sign-ins | | Email auth | SPF, DKIM, DMARC all pass | Improves deliverability for onboarding emails | Password resets land in spam or fail | | Monitoring | Uptime alerts plus error tracking enabled | Lets you catch failures fast | You find outages from customers first | | Deployment safety | Production deploy uses env vars and rollback path | Avoids accidental downtime during launch | Broken release blocks the whole launch |

The Checks I Would Run First

1. Authentication is actually enforced on every protected route

Signal: I look for any endpoint that returns user data without a valid session or bearer token. A single missed route is enough to fail launch readiness.

Tool or method: I test with Postman or curl using no token, expired token, wrong tenant token, and a valid low-privilege token. I also inspect middleware coverage in the API routes.

Fix path: I put auth at the edge of the request flow, not inside scattered handlers. If the app has mixed public and private routes, I separate them cleanly and add tests for deny-by-default behavior.

2. Authorization is tenant-safe, not just logged-in safe

Signal: A user should never be able to change `user_id`, `org_id`, `workspace_id`, or `account_id` in a request body or URL and reach another customer's data.

Tool or method: I run object-level access tests against read/update/delete endpoints. I try ID swapping between two accounts and check whether records leak across tenants.

Fix path: I enforce authorization server-side from session claims or lookup context only. I do not trust IDs coming from the client unless they are checked against the authenticated identity.

3. Secrets are not exposed anywhere public

Signal: No API keys in frontend code, build output, Git history snapshots, logs, error pages, or browser network responses.

Tool or method: I scan the repo with secret detection tools plus a manual search for common key patterns. I also inspect deployed bundles and environment configs.

Fix path: Anything sensitive moves to server-side env vars immediately. If a secret already shipped publicly, I rotate it before launch because exposure is a business incident, not a style issue.

4. CORS is strict enough for production but not so strict it breaks the app

Signal: Browser-based requests only work from approved domains. Wildcard origins combined with credentialed requests are a red flag unless there is a very specific reason.

Tool or method: I test requests from allowed and disallowed origins in devtools and via preflight checks. I confirm cookies and auth headers behave as expected.

Fix path: I whitelist exact domains for production plus staging where needed. If multiple subdomains are involved, I define them explicitly instead of using broad wildcard rules.

5. Rate limits exist on login, signup, password reset, webhook intake, and AI endpoints

Signal: Repeated requests trigger throttling before your database or third-party APIs get hammered.

Tool or method: I simulate burst traffic with a simple load script or API client loop. I watch status codes and response times while checking logs for abuse patterns.

Fix path: I set endpoint-specific limits based on risk. Login might allow 5 to 10 attempts per minute per IP; webhook intake needs signature checks plus replay protection; AI routes need cost-aware caps.

6. Production deployment uses correct environment variables and monitoring

Signal: The live app points at production databases only through env vars. Health checks work. Uptime alerts fire to email or Slack within minutes of failure.

Tool or method: I verify deployment config in the host dashboard plus runtime logs after deploy. Then I force one safe failure to confirm monitoring works end-to-end.

Fix path: I separate dev/staging/prod configs cleanly and document every required variable. For marketplace launches, this is non-negotiable because one wrong env var can expose test data or break onboarding across all users.

## Example production-only settings
NODE_ENV=production
API_BASE_URL=https://api.example.com
CORS_ORIGIN=https://app.example.com
SESSION_SECRET=replace-me
DATABASE_URL=replace-me

Red Flags That Need a Senior Engineer

• You have more than one auth system mixed together.

That usually means session cookies in one place and bearer tokens somewhere else with inconsistent protection.

• Your frontend calls internal admin endpoints directly.

That creates privilege escalation risk if someone can copy requests from browser devtools.

• You cannot explain where secrets live.

If nobody knows whether keys are in GitHub Actions, Vercel env vars, local `.env` files, or chat history exports, you need cleanup before launch.

• Your app already leaked customer data in testing.

One leak often means authorization logic is inconsistent across routes.

• Marketplace launch depends on email verification but SPF/DKIM/DMARC are failing.

That causes broken onboarding, password reset failures, and support load on day one.

DIY Fixes You Can Do Today

1. Remove any secret from frontend code immediately. If an API key appears in React code or browser bundles, assume it is compromised until rotated.

2. Turn on HTTPS everywhere. Force redirects from HTTP to HTTPS on all domains and subdomains before any paid traffic arrives.

3. Lock down CORS to exact production origins. Do not leave `*` in place if credentials are involved.

4. Add basic rate limiting to login and password reset. This cuts brute-force attempts and reduces abuse costs fast.

5. Verify SPF/DKIM/DMARC before sending onboarding emails. If those fail now, your welcome flow will end up in spam later when volume increases.

Where Cyprian Takes Over

This is where Launch Ready becomes useful instead of another DIY checklist that stalls out halfway through.

If you have DNS problems - domain not pointing correctly - I handle domain setup in the first few hours so the app resolves cleanly across root domain and subdomains. If redirects are messy or SSL is failing across multiple hostnames, I fix that as part of deployment hardening so users do not hit browser warnings during signup.

If your security gap is around secrets handling - which is common with AI-built apps - I move sensitive values into proper environment variables, verify nothing leaked into client code or logs, and make sure production services only see what they need. That reduces breach risk before you start driving traffic from a marketplace listing.

If email deliverability is weak - especially SPF/DKIM/DMARC - I fix that because broken onboarding emails create fake churn before users even reach the product UI. If monitoring does not exist yet, I set uptime checks so you know within minutes when deployment breaks instead of hearing it from customers hours later.

Here is how the service maps to failures:

| Failure found in checklist | What Launch Ready delivers | |---|---| | DNS misconfigured | Domain setup plus DNS correction | | Broken redirects/subdomains | Redirect rules plus subdomain routing | | No SSL / invalid certs | Cloudflare + SSL setup | | Weak caching / slow delivery paths | Cloudflare caching configuration | | No DDoS protection layer | Cloudflare protection enabled | | Email auth failing | SPF/DKIM/DMARC setup | | Secrets exposed or unmanaged | Environment variables + secrets cleanup | | No production deploy discipline | Production deployment + handover checklist | | No visibility after launch | Uptime monitoring setup |

In practice that means one focused sprint that gets you from "works on my machine" to "safe enough to ship," without dragging launch out into another week of back-and-forth delays.

What "Ready" Looks Like Before Marketplace Launch

I would consider an AI-built SaaS app ready when these thresholds are met:

• Zero exposed secrets in repo history visible branches.
• No critical auth bypasses found in manual route testing.
• p95 API latency under 500ms for core user flows.
• HTTPS forced on every public entry point.
• SPF/DKIM/DMARC passing for outbound mail.
• Uptime monitoring active with alerts tested once.
• Redirects verified for root domain plus key subdomains.
• CORS restricted to known origins only.
• Production deployment uses env vars rather than hardcoded values.
• A rollback plan exists if the release breaks sign-in or billing.

If you miss two or more of those items right now - especially auth safety plus secrets handling - do not call it launch ready yet. Ship later by one day if needed; shipping insecurely costs more than waiting 48 hours for proper cleanup.

Delivery Map

References

• https://roadmap.sh/api-security-best-practices
• https://roadmap.sh/cyber-security
• https://roadmap.sh/code-review-best-practices
• https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
• https://owasp.org/www-project-api-security/

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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.*