Launch Ready API security Checklist for founder landing page: Ready for first 100 users in mobile-first apps?.

What "ready" means for a founder landing page aimed at the first 100 users

For this product, "ready" does not mean perfect. It means a mobile-first landing page can safely take traffic, collect leads, send emails, and point users into the app without leaking secrets, breaking auth, or creating support chaos.

If I were self-assessing, I would want to see all of this before spending on ads or launching to Product Hunt:

• The page loads in under 2.5s LCP on mobile.
• Forms submit reliably with no duplicate leads.
• No exposed API keys, webhook secrets, or admin URLs in the frontend bundle.
• Email delivery passes SPF, DKIM, and DMARC.
• Cloudflare is in front of the domain with SSL forced on.
• Production deploys use environment variables, not hardcoded secrets.
• Uptime monitoring is active and someone gets alerted if the page or API fails.
• There are no critical auth bypasses, broken CORS rules, or unauthenticated admin endpoints.
• Redirects and subdomains are mapped correctly so users do not hit dead links.
• The handover is documented enough that a founder can explain the setup in 10 minutes.

For the first 100 users, one bad failure matters more than a long feature list. A broken signup flow, slow page, or exposed secret can waste paid traffic and damage trust before you have any signal on product-market fit.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Domain and DNS | Main domain resolves correctly; www and apex redirect cleanly | Users need one canonical entry point | Duplicate content, broken links, SEO confusion | | SSL forced | HTTPS only; no mixed content | Protects user data and trust | Browser warnings, blocked forms | | Cloudflare on | DNS proxied where appropriate; DDoS protection active | Reduces downtime and abuse risk | Downtime from spikes or basic attacks | | Email auth | SPF, DKIM, DMARC all passing | Improves deliverability for onboarding emails | Emails land in spam or fail entirely | | Secrets safe | Zero exposed keys in code or frontend bundle | Prevents account takeover and billing abuse | API compromise, surprise charges | | Form security | Validation server-side; rate limits enabled | Stops spam and abuse on lead forms | Fake signups, noisy CRM data | | Auth boundaries | No public admin routes; least privilege enforced | Prevents unauthorized access | Data exposure and account misuse | | Monitoring live | Uptime checks plus alerting configured | Lets you react before users complain | Silent outages and lost leads | | Performance acceptable | Mobile LCP under 2.5s; INP under 200ms target | Mobile users bounce fast when pages are slow | Lower conversion and wasted ad spend | | Handover complete | Deploy steps, rollback path, env list documented | Founder can operate safely after launch | Dependency on one person and slower fixes |

The Checks I Would Run First

1. I verify the public attack surface first

Signal: I want to know exactly what is reachable from the internet: landing page routes, form endpoints, auth endpoints, admin paths, webhooks, and any API docs.

Tool or method: I map the app with browser inspection, route review, Cloudflare DNS records, server logs if available, and a quick crawl of the public site.

Fix path: Remove anything that should not be public. Put admin paths behind auth or IP restrictions. Hide internal docs. If a webhook endpoint must stay public, add signature verification and strict input validation.

2. I check whether secrets are actually secret

Signal: No API keys in frontend JavaScript bundles, source maps, Git history snippets served publicly, or environment dumps.

Tool or method: Search the repo for `sk_`, `pk_`, `secret`, `token`, `webhook`, `.env`, and inspect built assets in the browser dev tools.

Fix path: Move all sensitive values to server-side environment variables. Rotate anything exposed immediately. If a key was committed once, assume it is compromised even if you deleted it later.

## Example .env pattern
NEXT_PUBLIC_API_URL=https://api.example.com
STRIPE_SECRET_KEY=...
RESEND_API_KEY=...

3. I test form submission like an attacker would

Signal: The lead form accepts only valid inputs once per submission flow. It rejects obvious junk without blocking real users.

Tool or method: Submit empty payloads, very long strings, HTML tags, repeated posts from the same IP/device, and invalid email addresses. Watch server logs for duplicates.

Fix path: Validate on the server. Add rate limits per IP and per session. Use honeypot fields or lightweight bot protection. Return clear errors instead of generic failures so legitimate users can recover.

4. I validate email authentication before launch

Signal: SPF passes for your sender domain. DKIM signs outgoing mail. DMARC is set to at least `p=quarantine` once tested.

Tool or method: Send test mail to Gmail and Outlook accounts. Check headers with MXToolbox or your email provider diagnostics.

Fix path: Set DNS records correctly through Cloudflare or your registrar. Align your From domain with your sending service. If onboarding emails are going to spam now with zero volume pressure applied yet, they will get worse at scale.

5. I confirm Cloudflare is doing real work

Signal: Traffic goes through Cloudflare where intended. SSL is enforced. Caching rules do not break dynamic pages. DDoS protection is active.

Tool or method: Inspect response headers like `cf-ray`, verify TLS mode in Cloudflare dashboard, test redirects from HTTP to HTTPS and apex to www if needed.

Fix path: Turn on full SSL mode only if origin certs are correct. Cache static assets aggressively but bypass cache for authenticated routes and form submissions. Do not cache personalized responses by accident.

6. I check observability before launch traffic starts

Signal: You know when the site goes down and when forms fail.

Tool or method: Set uptime checks every 1 minute from at least two regions plus error alerts for failed submissions and server errors over threshold.

Fix path: Add simple monitoring first instead of waiting for a full analytics stack. A founder needs alerting more than dashboards at this stage. If p95 API latency crosses 500ms on core form submission paths during load tests, fix that before ads go live.

Red Flags That Need a Senior Engineer

1. You have multiple environments but no clear separation between dev and prod secrets.

• This creates accidental data leaks and broken deploys that are hard to unwind.

2. The landing page talks to third-party APIs directly from the browser using secret-bearing requests.

• That is usually an avoidable security mistake that exposes credentials.

3. You do not know where form submissions go after capture.

• Lost leads are silent revenue loss disguised as "low demand."

4. Your current setup depends on manual deploy steps with no rollback plan.

• One bad release can take down signups for hours while you scramble.

5. You have already seen spam signups or weird traffic spikes during testing.

• That usually means bot controls are weak now and will fail harder after launch.

DIY Fixes You Can Do Today

1. Change every password you reused across hosting, email, domain registrar accounts.

• Use unique passwords plus MFA everywhere possible.

2. Turn on HTTPS redirects in your hosting platform or Cloudflare.

• Test both `http://` and `https://` versions of the site manually on mobile.

3. Audit your repo for secrets before pushing another commit.

• Search `.env`, build files ,and old branches if needed.

4. Set up SPF now even if DKIM/DMARC take longer.

• Partial email setup is better than sending from an unauthenticated domain forever.

5. Add one uptime monitor today.

• Even a basic ping check is better than finding out about downtime from a user screenshot.

Where Cyprian Takes Over

Here is how checklist failures map to the service deliverables:

| Failure found | What I fix in Launch Ready | |---|---| | Bad DNS or broken redirects | Domain setup ,DNS cleanup ,redirect mapping ,subdomain routing | | No SSL or mixed content issues | Cloudflare config ,SSL enforcement ,origin hardening | | Slow mobile landing page | Caching rules ,asset optimization ,deployment tuning | | Exposed secrets risk | Environment variable cleanup ,secret rotation guidance ,handover checklist | | Spammy forms or weak abuse controls | Form hardening ,rate limiting ,basic anti-abuse setup | | Email delivery problems | SPF/DKIM/DMARC configuration ,sender alignment | | Unclear production release process | Production deployment ,rollback notes ,handover documentation | | No visibility after launch | Uptime monitoring setup ,alerting configuration |

My typical sequence is simple:

1. Hour 0-8: audit domain ,email ,hosting ,and current exposure risks. 2. Hour 8-24: fix DNS ,Cloudflare ,SSL ,and deployment issues. 3. Hour 24-36: clean up secrets ,environment variables ,and monitoring. 4. Hour 36-48: verify handover checklist ,test critical flows again ,and document what changed.

The goal is not just "it works." The goal is "it works safely enough to send traffic today."

If you are about to spend money on ads or announce publicly but cannot answer these questions confidently:

• Where do leads go?
• Which secrets are exposed?
• Who gets alerted if signup breaks?
• Is email authenticated?
• Is production behind Cloudflare?

then you do not need another design tweak first .You need launch hardening first .

Delivery Map

References

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

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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.*