Launch Ready API security Checklist for subscription dashboard: Ready for first 100 users in mobile-first apps?.

Launch Ready API security Checklist for subscription dashboard: Ready for first 100 users in mobile-first apps?

"Ready" for a subscription dashboard is not "it works on my phone". It means a new user can sign up, pay, log in, and manage their subscription without exposing customer data, breaking auth, or creating support debt on day one.

For a mobile-first app targeting the first 100 users, I would call it ready only if these are true:

• No critical auth bypasses.
• Zero exposed secrets in the repo, build logs, or client bundle.
• p95 API response time under 500ms for core dashboard actions.
• Login, billing, and account recovery work on iOS and Android browsers.
• SPF, DKIM, and DMARC all pass for transactional email.
• Cloudflare, SSL, redirects, and environment separation are in place.
• Uptime monitoring is live before launch, not after the first outage.

If any of those fail, you do not have a launch-ready product. You have a prototype with a payment button.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Auth enforcement | Every protected route and API returns 401 or 403 when unauthenticated or unauthorized | Prevents account takeover and data leaks | Users can see other accounts or admin actions | | Session handling | Tokens expire, refresh safely, and are stored correctly for mobile web or app clients | Reduces hijacking risk | Stolen tokens stay valid too long | | Input validation | All API inputs are validated server-side with allowlists and schema checks | Stops bad data and injection paths | Broken records, abuse, and security bugs | | Rate limiting | Login, OTP, password reset, and high-cost endpoints are limited | Protects against brute force and abuse | Support load spikes and account attacks | | Secrets hygiene | No keys in code, logs, client env files, or public repos | Prevents direct infrastructure compromise | Stripe, email, or database access leaks | | CORS policy | Only approved origins can call your APIs from browsers | Stops cross-origin abuse | Third-party sites can hit your API from the browser | | Billing webhook verification | Webhooks are signed and verified before any state change | Stops fake subscription events | Free access or false cancellations | | Email domain auth | SPF/DKIM/DMARC pass for transactional email domains | Improves deliverability and trust | Password resets land in spam or never arrive | | Observability | Errors, auth failures, webhook failures, and latency are logged with alerts | Lets you catch issues before users complain | Silent failures pile up into churn | | Production deploy safety | SSL active, redirects correct, Cloudflare configured, rollback possible | Reduces launch-day breakage | Downtime, mixed content errors, broken login |

The Checks I Would Run First

1. Authentication cannot be bypassed by guessing routes or IDs

Signal:

• A user cannot access another user's dashboard by changing an ID in the URL or API request.
• Protected endpoints return 401 or 403 consistently.
• Admin-only actions fail for normal users every time.

Tool or method:

• Manual testing with Postman or Insomnia.
• Browser dev tools to inspect network calls.
• Simple ID swapping tests against `/api/subscription/:id`, `/api/account/:id`, or similar routes.

Fix path:

• Enforce authorization on every request server-side.
• Do not trust frontend checks alone.
• Use object-level authorization rules tied to the authenticated user.
• If you find one bypass path here, assume there are more.

2. Subscription state comes only from verified billing webhooks

Signal:

• Plan changes happen only after verified webhook events from Stripe or your billing provider.
• Fake requests to webhook endpoints do nothing.
• Duplicate events do not create duplicate upgrades.

Tool or method:

• Replay webhook payloads locally with invalid signatures.
• Review event logs in Stripe dashboard.
• Check whether idempotency keys exist.

Fix path:

• Verify webhook signatures before processing.
• Store processed event IDs to prevent double processing.
• Never grant paid access based only on frontend success screens.
• If billing drives access control and webhooks are weak, you have revenue leakage risk.

3. Secrets are not exposed anywhere a browser can see them

Signal:

• No API keys appear in client-side bundles.
• No `.env` values leak into logs or public repos.
• No production credentials live in local config files shared by accident.

Tool or method:

• Search the repo for `sk_`, `pk_`, `secret`, `token`, `private_key`.
• Inspect built JS bundles for accidental leakage.
• Run secret scanning with GitHub secret scanning or TruffleHog.

Fix path:

• Move secrets to server-only environment variables.
• Rotate anything already exposed immediately.
• Separate public keys from private keys clearly.
• If you need to ask whether a key is safe to expose to mobile clients, treat it as unsafe until proven otherwise.

4. Rate limits exist on all expensive and sensitive endpoints

Signal:

• Login attempts slow down after repeated failures.
• Password reset requests cannot be spammed endlessly.
• Subscription lookup endpoints cannot be hammered without consequence.

Tool or method:

• Use k6 or simple repeated curl requests.
• Test from multiple IPs if possible.
• Review logs for throttling behavior.

Fix path:

/login: 5 attempts per 10 min per IP + account
/reset-password: 3 attempts per hour per account
/api/*: limit by route cost

Implement rate limiting at the edge where possible. Add stricter controls around auth and billing endpoints. Without this layer, first-week abuse can become first-week downtime.

5. Email authentication is passing before launch

Signal:

• SPF passes for your sender domain.
• DKIM signs outgoing mail correctly.
• DMARC is set to at least `p=quarantine` during launch testing.

Tool or method:

• Use MXToolbox checks.
• Send test emails to Gmail and Outlook accounts.
• Inspect message headers for SPF/DKIM/DMARC results.

Fix path:

v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com; adkim=s; aspf=s

Add SPF records only for approved senders. Set up DKIM signing through your email provider. If password resets fail here, users will think login is broken even when your app is fine.

6. Production deployment has basic security controls turned on

Signal:

• SSL is active everywhere.
• HTTP redirects to HTTPS work cleanly.
• Cloudflare protects the origin where applicable.
• Uptime monitoring alerts you before customers do.

Tool or method:

• Visit key pages over HTTP and HTTPS.

-Try subdomains like `app.domain.com`, `api.domain.com`, and `www.domain.com`. -Test certificate validity with SSL Labs.

Fix path: Use one deployment owner per environment. Lock down origin access where possible. Confirm caching rules do not cache private dashboard pages. If private user data can be cached publicly by mistake, that is a serious incident waiting to happen.

Red Flags That Need a Senior Engineer

1. You have no idea which requests require auth versus which ones just "work".

• That usually means hidden authorization bugs across multiple routes.

2. Billing logic lives partly in frontend code and partly in random server functions.

• This creates inconsistent subscription state and support tickets that are hard to unwind.

3. The app uses multiple AI-built tools but nobody can explain where secrets live.

• This is how API keys end up in client bundles or public repos.

4. Password reset emails sometimes arrive late or go to spam already during beta testing.

• At scale this becomes failed onboarding and lost revenue.

5. You are planning launch ads before you have uptime monitoring and rollback tested once end-to-end.

• That turns paid traffic into wasted spend if the first outage hits during acquisition.

DIY Fixes You Can Do Today

1. Audit your repo for secrets now

• Search for private keys, tokens, `.env`, service account files, Stripe secrets, OpenAI keys, Firebase admin keys.

2. Confirm every protected endpoint rejects anonymous access

• Log out completely and test dashboard pages plus API calls manually.

3. Turn on basic rate limits

• Start with login and password reset first. Those two endpoints attract abuse quickly.

4. Verify your email DNS records

• SPF must pass. DKIM must pass. DMARC should at least be present before launch.

5. Check what is actually public in your build output

• Open the deployed JS bundle search results in browser dev tools if needed. Anything there should be assumed exposed forever once indexed by attackers.

Where Cyprian Takes Over

What I cover:

| Failure found | Launch Ready deliverable | |---|---| | Domain setup confusion | DNS cleanup, redirects, subdomains | | SSL errors / mixed content / bad certs | Cloudflare setup plus SSL verification | | Exposed secrets / broken env config | Environment variable cleanup and secret handling review | | No production deployment discipline | Production deployment with handover checklist | | Missing email trust signals | SPF/DKIM/DMARC setup | | No observability / silent failures | Uptime monitoring setup | | Slow first-load experience from bad edge config | Caching review at the edge | | Origin exposure / basic attack surface issues | Cloudflare DDoS protection configuration |

My delivery order is simple:

1. Hour 0 to 8: audit domain routing, deployment target(s), secrets exposure risk, email sending setup. 2. Hour 8 to 24: fix DNS records,, SSL,, redirects,, subdomains,, environment variables,, caching,,and origin protection issues that can block launch . 3. Hour 24 to 36: verify production deploy,, test transactional email,, confirm uptime monitoring,,and document handover steps . 4 . Hour36to48 : final QA pass ,, rollback check ,,and founder handover .

For a first100-user launch ,I care less about fancy architectureand more about preventing avoidable failure : leaked credentials ,broken login ,failed receipts ,spam-folder emails ,and no alert when things go down .

If you want me to pressure-test this before users do ,book here : https://cal.com/cyprian-aarons/discovery

References

1. roadmap.sh code review best practices: https://roadmap.sh/code-review-best-practices 2. roadmap.sh api security best practices: https://roadmap.sh/api-security-best-practices 3. OWASP API Security Top 10: https://owasp.org/API-Security/ 4. Cloudflare security docs: https://developers.cloudflare.com/security/ 5. Google Postmaster Tools for email deliverability: https://support.google.com/postmaster/answer/6227309

---

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.*