Launch Ready API security Checklist for founder landing page: Ready for handover to a small team in marketplace products?.

What "ready" means for a founder landing page in marketplace products

For this product, "ready" does not mean pretty. It means a small team can take over without breaking domain routing, exposing secrets, or shipping a landing page that sends traffic into a fragile backend.

I would call it ready only if a new teammate can verify these outcomes in under 30 minutes: the domain resolves correctly, SSL is valid, redirects are clean, email deliverability passes SPF/DKIM/DMARC, no secrets are exposed in the repo or browser, monitoring is live, and the page can survive launch traffic without obvious security or uptime risk.

For marketplace products specifically, the landing page usually sits at the top of a funnel that feeds signups, waitlists, vendor onboarding, buyer onboarding, or early payments. If API security is weak here, the failure is not just technical; it becomes broken lead capture, fake signups, spam abuse, support load, and wasted ad spend.

My standard for "handover ready" is simple:

• No critical auth bypasses.
• Zero exposed secrets.
• SPF, DKIM, and DMARC all passing.
• Uptime monitoring active.
• DNS and redirects documented.
• Production deployment reproducible by a small team.
• Landing page performance strong enough to keep LCP under 2.5s on mobile for the main route.

If any one of those is missing, I would not hand it to a junior team and hope for the best.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | Domain setup | Root and www resolve to intended host | Users and ads must land on the right page | Lost traffic, SEO split, broken campaigns | | SSL | HTTPS valid on all public routes | Trust and browser compatibility | Warning screens, blocked forms | | Redirects | One canonical path per URL | Prevents duplicate content and confusion | SEO dilution, redirect loops | | Email auth | SPF, DKIM, DMARC all pass | Inbox placement for marketplace emails | Emails go to spam or fail | | Secrets handling | No secrets in client bundle or repo history | Prevents account takeover and data exposure | Credential theft, abuse costs | | API auth | No unauthenticated sensitive endpoints | Stops data leaks and fake actions | Exposed user data, fraud | | Rate limits | Abuse controls on forms and APIs | Protects against bots and scraping | Spam floods, cost spikes | | Monitoring | Uptime alerts + error alerts active | Small teams need fast detection | Silent downtime and delayed response | | Deployment repeatability | Clear steps or CI deploy works twice in a row | Handover depends on reproducibility | "Works on my machine" failures | | Performance baseline | LCP under 2.5s on mobile home route | Conversion drops when pages are slow | Lower signup rate and ad waste |

The Checks I Would Run First

1. Domain and redirect map

Signal:

• `example.com`, `www.example.com`, and any campaign subdomains all land where they should.
• There are no redirect chains longer than one hop.
• Old URLs do not loop or 404.

Tool or method:

• Browser checks plus `curl -I`.
• DNS lookup with `dig`.
• A simple redirect inventory spreadsheet.

Fix path:

• Set one canonical domain.
• Add explicit 301 redirects from old paths.
• Document every subdomain used by marketing, app login, email tracking, or admin access.

2. SSL and Cloudflare edge posture

Signal:

• HTTPS works everywhere.
• No mixed content warnings.
• Cloudflare proxying is configured intentionally.
• DDoS protection is enabled for public entry points.

Tool or method:

• Browser devtools security tab.
• SSL Labs test.
• Cloudflare dashboard review.

Fix path:

• Force HTTPS at the edge.
• Replace hardcoded `http://` asset URLs.
• Put only public assets behind cache rules.
• Lock down origin access so traffic cannot bypass Cloudflare unless explicitly needed.

3. Secrets exposure check

Signal:

• No API keys in frontend code.
• No `.env` values committed to git history.
• No tokens visible in build output or network logs.

Tool or method:

• Search repo history with `git log -p` and secret scanners like Gitleaks or TruffleHog.
• Inspect browser bundles for accidental key exposure.

Fix path:

• Rotate anything exposed immediately.
• Move server-only values out of frontend code.
• Use environment variables only on trusted server runtimes.

A good rule: if a key can be read by the browser, assume it is already public.

4. API authorization review

Signal:

• Sensitive endpoints require auth where needed.
• Role checks exist for admin actions.
• Users cannot access other users' records by changing IDs.

Tool or method:

• Manual test with two accounts.
• Try ID swapping in requests.
• Review middleware and route guards.

Fix path:

• Enforce authorization on every object access layer.
• Do not trust client-side role flags.
• Add deny-by-default behavior for marketplace admin routes.

5. Form abuse and rate limiting

Signal:

• Signup forms do not accept unlimited submissions from one IP or device fingerprint.
• Bot traffic does not flood your CRM or inbox.
• Repeated requests return controlled errors instead of creating duplicates.

Tool or method:

curl -X POST https://yourdomain.com/api/signup \
  -H "Content-Type: application/json" \
  -d '{"email":"test@example.com"}'

Run that repeatedly from one source and watch what happens.

Fix path:

• Add rate limits at the edge and API layer.
• Add honeypot fields and basic bot detection to forms.
• Deduplicate submissions by email plus source context.

6. Monitoring and handover readiness

Signal:

• Someone gets alerted when the site goes down or returns elevated errors.
• Logs show enough context to debug without exposing sensitive data.
• A new teammate can find deployment steps in one place.

Tool or method:

• Check uptime monitors like UptimeRobot or Better Stack.
• Review alert routing to email/Slack/SMS.
• Read through deployment docs as if you were new to the project.

Fix path:

SPF=pass
DKIM=pass
DMARC=pass
UPTIME_ALERTS=on
ERROR_ALERTS=on

That snippet is not code to run; it is the minimum operational state I want documented before handover.

Red Flags That Need a Senior Engineer

1. You have loginless APIs that still expose user-specific data. That usually means authorization was bolted on late or skipped entirely. This is how marketplace products leak profiles, listings, invoices, or leads.

2. The app has multiple environments but no clear secret separation. If staging keys work in production or vice versa, someone will eventually ship with the wrong credentials. That creates downtime at best and data exposure at worst.

3. The landing page talks to third-party services directly from the browser using private keys. That is an easy way to burn through quotas or expose account access. I would move those calls server-side immediately.

4. Deployments are manual and undocumented. If only one person knows how production gets updated, handover is fake. Small teams need repeatable release steps with rollback clarity.

5. You cannot explain who owns DNS, email auth, hosting, monitoring, and incident response. When these responsibilities are unclear during launch week, nobody reacts fast enough when something breaks.

DIY Fixes You Can Do Today

1. Check your public DNS records Make sure root domain records point to the correct host and that unused subdomains are removed or parked properly. This prevents accidental exposure through forgotten services.

2. Turn on SPF/DKIM/DMARC If your marketplace sends confirmations, invites, receipts, or onboarding emails without these records passing validation checks will hurt delivery rates fast.

3. Rotate any key you have ever pasted into chat tools If you shared an API key with an assistant tool while building fast with Lovable, Bolt, Cursor, v0, Webflow automation hooks ,or similar tools treat it as compromised until rotated.

4. Review your frontend bundle for secrets Search for strings like `sk_`, `pk_`, `api_key`, `secret`, `token`, `Bearer`, and private service URLs. If they appear in client code where they should not be visible remove them before launch traffic finds them first.

5. Set up basic uptime monitoring now Even a simple ping monitor is better than nothing. A small team cannot fix what it does not know is broken until users complain publicly.

Where Cyprian Takes Over

This is where I step in when DIY stops being safe enough for launch week.

If I find secret sprawl,, I audit environment variables,, remove exposed credentials,, separate staging from production,,and document what belongs where so your small team can inherit it without guessing.

If I find weak edge protection,, I configure Cloudflare,, caching,, DDoS protection,,and production deployment guardrails so your landing page survives real traffic instead of collapsing under bot noise or launch spikes .

If I find poor email deliverability,, I set up SPF/DKIM/DMARC so marketplace invitations,, waitlist confirmations,,and onboarding emails actually reach inboxes .

If monitoring is missing,, I add uptime checks plus handover notes so your team knows what to watch after launch instead of discovering failures from angry users first .

Delivery timeline Day 1: - audit current state, - fix DNS, - lock down SSL, - clean redirects, - review secrets, - confirm deployment path .

Day 2: - enable caching, - finalize Cloudflare rules, - configure email authentication, - add monitoring, - produce handover checklist, - walk the small team through ownership boundaries .

The goal is not just "deployed." The goal is "another person can safely run this next week."

Mermaid Diagram

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. roadmap.sh Cyber Security: https://roadmap.sh/cyber-security 4. OWASP Top 10: https://owasp.org/www-project-top-ten/ 5. Cloudflare Docs: https://developers.cloudflare.com/

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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.*