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

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

For this product and outcome, "ready" means your landing page can survive a real security review without creating avoidable risk for the marketplace behind it. I would expect zero exposed secrets, no broken auth or API exposure from the public site, SPF/DKIM/DMARC all passing, Cloudflare in front of the domain, SSL enforced everywhere, and monitoring in place before launch.

If I were self-assessing this as a founder, I would want to answer yes to all of these:

• The page loads over HTTPS only.
• No API keys, tokens, or private endpoints are visible in the browser, source code, or logs.
• Forms cannot be abused for spam, injection, or account enumeration.
• Third-party scripts are limited and reviewed.
• DNS, email, redirects, and subdomains are configured correctly.
• If the page goes down or gets attacked, I know within minutes.

For marketplace products specifically, the landing page is not just marketing. It is often the first attack surface before signup, onboarding, payment flow, partner access, or seller/admin portals. If this layer is sloppy, security reviewers assume the rest of the stack is also sloppy.

Quick Scorecard

| Check | Pass criteria | Why it matters | What breaks if it fails | |---|---|---|---| | HTTPS only | All HTTP traffic redirects to HTTPS with no mixed content | Prevents interception and trust loss | Browser warnings, leaked form data | | Cloudflare active | DNS proxied through Cloudflare with WAF and DDoS on | Reduces attack surface and absorbs traffic spikes | Easy bot abuse and downtime | | Secrets hidden | No keys in frontend code, repo history, or environment dumps | Stops direct compromise of APIs and services | Data exfiltration and bill shock | | Email auth passes | SPF, DKIM, DMARC all passing | Protects domain reputation and deliverability | Emails land in spam or get spoofed | | Forms hardened | Rate limits, CAPTCHA or honeypot, validation on server | Blocks spam and abuse at scale | Fake leads, support load, bad data | | CORS locked down | Only approved origins can call APIs | Prevents cross-site misuse of endpoints | Unauthorized browser-based access | | Security headers set | CSP, HSTS, X-Frame-Options or frame-ancestors present | Reduces XSS and clickjacking risk | Script injection and UI redress attacks | | Redirects clean | One canonical domain path with no loops or chains > 1 hop | Keeps trust and SEO intact | Broken login links and review delays | | Monitoring live | Uptime alerts plus error tracking active within 5 min alerts | Lets you detect failures fast | Silent outages and missed incidents | | API exposure reviewed | Public site cannot reach admin-only or internal APIs directly | Stops accidental privilege exposure | Auth bypasses and data leaks |

The Checks I Would Run First

1. I would inspect every request the page makes

• Signal: The browser network tab shows calls only to approved public endpoints. No admin routes, internal hostnames, or raw third-party secrets appear.
• Tool or method: Chrome DevTools Network tab plus a quick grep through the built assets.
• Fix path: Remove direct client calls to privileged APIs. Put sensitive logic behind server-side endpoints with auth checks and rate limits.

2. I would verify there are no exposed secrets

• Signal: No API keys in frontend bundles, source maps, Git history snapshots, env files committed by accident, or HTML comments.
• Tool or method: `git grep`, secret scanning in GitHub/GitLab, browser bundle inspection.
• Fix path: Rotate any leaked key immediately. Move secrets to environment variables on the server only. Rebuild assets after removal.

3. I would test email authentication end to end

• Signal: SPF passes for your sending service. DKIM signs messages correctly. DMARC passes with alignment.
• Tool or method: MXToolbox or Google Postmaster Tools plus a real test send to Gmail and Outlook.
• Fix path: Publish correct DNS records for your mail provider. Start DMARC at `p=none`, then move to `quarantine` after validation.

4. I would check redirect behavior from every entry point

• Signal: `http://`, `https://`, `www`, non-www, apex domain, campaign URLs, and subdomains all resolve predictably with one canonical destination.
• Tool or method: `curl -I` against each variant plus Cloudflare redirect rules review.
• Fix path: Create one canonical route map. Remove redirect chains and loops. Force HTTPS at edge level.

5. I would review security headers on the public page

• Signal: CSP exists with restricted script sources. HSTS is enabled. Framing is blocked. MIME sniffing is off.
• Tool or method: SecurityHeaders.com plus response header inspection in DevTools.
• Fix path: Add headers at Cloudflare or your hosting layer. Tighten CSP until only required scripts run.

6. I would try basic abuse cases against forms

• Signal: Form submissions reject malformed input gracefully. Spam bursts are throttled. Bots do not create fake records repeatedly.
• Tool or method: Manual testing plus one simple script sending repeated requests.
• Fix path: Add server-side validation, rate limiting per IP and per session, honeypot fields if appropriate, CAPTCHA only where needed.

Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted-cdn.example; object-src 'none'; frame-ancestors 'none'

That line matters because a weak landing page often becomes the easiest place for an attacker to inject scripts that steal form data or hijack sessions later in the funnel.

Red Flags That Need a Senior Engineer

1. The landing page talks directly to private marketplace APIs

• That usually means auth boundaries are already blurred.

2. You have secrets inside frontend env files

• If a key ships to the browser once, assume it is already public.

3. You are using multiple domains without a canonical plan

• Reviewers see this as sloppy infrastructure hygiene.

4. Your forms write straight into production systems without validation

• This creates spam risk now and data quality problems later.

5. You do not know who owns DNS, email DNS records, SSL renewals, or monitoring

• Missing ownership causes launch delays when something breaks at 2 am.

DIY Fixes You Can Do Today

1. Turn on HTTPS redirect everywhere

• Make sure every HTTP request goes to HTTPS with no exceptions.
• Check apex domain and `www` separately.

2. Rotate any secret you have ever pasted into a chat tool

• Treat copied keys as compromised unless proven otherwise.

3. Audit your email DNS records

• Confirm SPF includes only your sender.
• Confirm DKIM signing is active.
• Publish DMARC so spoofing gets blocked.

4. Remove unused third-party scripts

• Kill old analytics tags before they become privacy and performance baggage.
• Every extra script adds risk and slows LCP.

5. Add basic monitoring now

• Set uptime alerts for homepage availability and SSL expiry.
• Set error alerts for form failures so leads do not disappear silently.

Where Cyprian Takes Over

Here is how I map failures to deliverables:

| Failure type | Launch Ready deliverable | Timeline | |---|---|---| | Domain misconfigurations | DNS cleanup, redirects, subdomain mapping | Hours 1-6 | | Weak email deliverability | SPF/DKIM/DMARC setup and verification | Hours 3-8 | | Missing SSL / mixed content | SSL enforcement plus asset cleanup | Hours 2-6 | | Exposed secrets / env issues | Secret audit plus environment variable hardening | Hours 4-12 | | Public API exposure risk | Endpoint review plus access boundary fixes | Hours 6-18 | | No Cloudflare protection | Cloudflare setup with caching and DDoS protection on edge rules applied correctly | Hours 6-14 | | No monitoring / no handover plan | Uptime monitoring setup plus owner checklist | Hours 12-24 |

My recommendation is simple: if you are preparing for a security review on a marketplace product landing page within days of launch, do not spend two weeks learning infrastructure basics from scratch. Buy the sprint when you need fewer surprises, faster approval, and less chance of shipping something that gets flagged by reviewers anyway.

delivered in 48 hours, and includes:

• DNS
• redirects
• subdomains
• Cloudflare
• SSL
• caching
• DDoS protection
• SPF/DKIM/DMARC
• production deployment
• environment variables
• secrets handling
• uptime monitoring
• handover checklist

That scope is designed to reduce launch delay, avoid broken onboarding paths, prevent exposed customer data, and cut support load before paid traffic starts hitting the page.

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 roadmap: https://roadmap.sh/cyber-security
• OWASP Top 10: https://owasp.org/www-project-top-ten/
• Cloudflare security docs: https://developers.cloudflare.com/security/

---

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.*