Launch Ready API security Checklist for founder landing page: Ready for production traffic in marketplace products?.

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

For a marketplace product, "launch ready" does not mean the page just loads and looks good in staging. It means real buyers can hit the landing page from ads, email, social, or direct traffic without broken forms, exposed secrets, weak DNS, failed auth checks, or support chaos.

I would call it ready only if these are true:

• The domain resolves correctly with HTTPS forced everywhere.
• Email deliverability is working with SPF, DKIM, and DMARC passing.
• The page loads fast enough for paid traffic, with LCP under 2.5s on mobile.
• Forms and API calls do not expose keys, tokens, or internal endpoints.
• Cloudflare is protecting the site from basic abuse and DDoS noise.
• Monitoring is in place so you know within minutes if checkout, signup, or lead capture breaks.
• Redirects, subdomains, and environment variables are configured without manual hacks.
• There are no critical auth bypasses, no open admin routes, and no insecure CORS settings.

If any of those fail, you are not ready for production traffic. You are buying ad spend that can get wasted on broken onboarding, failed lead capture, support tickets, and lost trust.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | HTTPS enforced | All HTTP requests 301 to HTTPS | Prevents mixed content and trust issues | Browser warnings, lower conversion | | DNS correct | A/CNAME records resolve to live app | Traffic reaches the right environment | Site outage or wrong version live | | SPF/DKIM/DMARC passing | All three pass on test send | Improves deliverability and sender trust | Emails land in spam or get rejected | | Secrets removed from client | Zero exposed API keys in browser code | Stops abuse and billing leaks | Account takeover risk and cost spikes | | CORS locked down | Only approved origins allowed | Protects APIs from unwanted cross-site calls | Data exposure or broken integrations | | Auth routes protected | No admin or private endpoints public | Prevents unauthorized access | Data leak or account compromise | | Redirects clean | WWW/non-WWW and subdomain rules consistent | Avoids duplicate pages and SEO loss | Broken links and split analytics | | Cloudflare enabled | WAF/CDN/DDoS protection active | Reduces noise and basic attacks | Downtime under bot traffic | | Monitoring active | Uptime alert within 5 minutes of failure | Lets you react before revenue drops | Silent outage during launch | | Performance acceptable | LCP under 2.5s on mobile; CLS under 0.1 | Paid traffic converts better when fast | Higher bounce rate and wasted ads |

The Checks I Would Run First

1) I verify the public attack surface first Signal: The landing page exposes only what it needs: public marketing content, form submission endpoint(s), and nothing sensitive in source maps or network calls.

Tool or method: I inspect the browser devtools network tab, run a quick curl scan of known routes, and check whether source maps are publicly accessible. I also search the frontend bundle for hardcoded keys.

Fix path: Move secrets out of client code immediately. If any private endpoint is reachable without auth or rate limits, I block it behind server-side checks. If source maps reveal internals during launch week, I disable them in production until they are sanitized.

2) I test authentication boundaries like an attacker would Signal: Admin pages, webhook handlers, internal dashboards, and marketplace moderation tools require proper auth every time.

Tool or method: I use direct URL access tests with logged-out sessions, incognito sessions, and a second low-privilege account. I also try tampering with cookies and tokens to see if access control fails open.

Fix path: Add server-side authorization checks on every sensitive route. Do not trust hidden UI buttons as security. If role checks live only in frontend code, I move them to backend middleware before launch.

3) I check CORS and API exposure Signal: The API accepts requests only from approved origins and does not allow wildcard access where credentials are involved.

Tool or method: I review response headers for `Access-Control-Allow-Origin`, `Access-Control-Allow-Credentials`, and preflight behavior. Then I test requests from an unapproved origin.

Fix path: Lock CORS to explicit domains only. Never use `*` with credentialed requests. If the app needs multiple environments like `app.domain.com` and `staging.domain.com`, whitelist them intentionally.

A safe baseline looks like this:

const corsOptions = {
  origin: ["https://yourdomain.com", "https://www.yourdomain.com"],
  methods: ["GET", "POST"],
  credentials: true,
};

4) I validate email deliverability before any launch traffic Signal: SPF passes for your sender domain, DKIM signs outbound mail correctly, and DMARC is set to at least quarantine once tested.

Tool or method: I send test emails to Gmail and Outlook accounts and inspect authentication results in message headers. I also check DNS records directly.

Fix path: Set SPF to include only approved senders. Turn on DKIM signing in your email provider. Start DMARC at `p=none` during testing if needed, then move to `quarantine` once stable. If your welcome emails are failing now, your marketplace will struggle with activation later.

5) I measure performance against paid traffic standards Signal: Mobile LCP is under 2.5 seconds on a realistic connection profile. CLS stays under 0.1. INP does not feel laggy when forms submit.

Tool or method: Lighthouse plus real-device testing on throttled mobile networks. I also inspect image sizes, third-party scripts, font loading behavior, caching headers, and render-blocking assets.

Fix path: Compress hero images, defer non-critical scripts, remove unused libraries, preload key assets carefully, and cache static files through Cloudflare. If a landing page depends on heavy widgets before first paint is complete enough to convert visitors.

6) I confirm monitoring catches failures fast Signal: Uptime checks hit the live URL every minute or five minutes max; alerts go to email or Slack; logs capture errors without leaking secrets.

Tool or method: I simulate downtime by pointing a health check at a dead route or temporarily disabling a service in staging. Then I confirm alert timing end-to-end.

Fix path: Add uptime monitoring plus error tracking before launch day ends. Set alerts for HTTP 500 spikes, form submission failures, SSL expiry warnings around day 30+, and DNS changes that break resolution.

Red Flags That Need a Senior Engineer

If you see any of these during setup or review, DIY becomes expensive quickly:

1. API keys are present in frontend code

• This is not a cosmetic issue.
• It can become billing abuse or data exposure within hours of launch traffic.

2. The landing page submits directly to third-party tools without server validation

• That creates spam risk and makes abuse easy.
• Marketplace products get hit harder because bots scrape forms fast.

3. You have multiple domains but no clear redirect policy

• Duplicate content hurts SEO.
• Worse: customers may land on stale environments that still look "live."

4. Auth is handled mostly in the UI

• If the backend does not enforce permissions too,
• someone will eventually find a route that should never have been public.

5. You do not know what happens when the form fails

• No error state means lost leads.
• No retry logic means silent revenue loss during peak traffic windows.

DIY Fixes You Can Do Today

These are safe moves most founders can do before bringing me in:

1. List every domain you own

• Primary domain
• WWW version
• App subdomain
• Staging subdomain
• Email sending domain

2. Check SSL on all public URLs

• Make sure each one redirects to HTTPS.
• Remove any old links that still point to HTTP.

3. Audit environment variables

• Search for `.env`, build-time constants,
• hardcoded tokens,
• API keys inside React/Vite/Next public env names.
• Anything starting with `NEXT_PUBLIC_`, `VITE_`, or similar should be treated as public by default.

4. Run an email authentication test

• Use Gmail header inspection after sending from your domain.
• Confirm SPF/DKIM/DMARC pass before launch traffic starts.

5. Open the site on mobile over slow data

• If the hero takes forever,
• if buttons jump around,
• if forms lag,

then fix that before buying ads.

Where Cyprian Takes Over

When founders come to me with this checklist failing in multiple places, I do not start with redesign fluff. I start with production safety because that is what protects revenue.

Here is how Launch Ready maps to the failures:

| Failure area | What I fix in Launch Ready | Timeline | |---|---|---| | DNS misconfigurations | Domain setup, redirects between root/www/subdomains | Within first 6 hours | | Weak email setup | SPF/DKIM/DMARC configuration and verification | Within first 12 hours | | SSL issues | Certificate setup and HTTPS enforcement via Cloudflare/deployment config | Same day | | Secrets exposure | Environment variable cleanup and secret rotation plan | Same day | | Missing protection layer | Cloudflare CDN/WAF/DDoS setup + caching rules | First day | | Broken deployment flow | Production deployment validation across environments | First day | | No monitoring | Uptime monitoring + alert routing + basic logging handover | By hour 36 | | Unclear handover risk | Handover checklist with owner actions after launch window ends | By hour 48 |

My recommendation: do not spend three days trying to patch this yourself if you are about to send paid traffic into it tomorrow.

The handover includes what changed, what was verified, and what still needs owner attention after launch week. That matters because many founder launches fail not from code bugs alone but from missing operational ownership after deployment.

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 Docs: https://developers.cloudflare.com/
• Google Search Central on HTTPS: https://developers.google.com/search/docs/crawling-indexing/https-encryption

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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.*