SecurityHeaders.com Alternative for Continuous Security Monitoring.
SecurityHeaders.com's API is shutting down in April 2026. Here's what changes, who's affected, and how to monitor your security headers automatically going forward.
If you’ve ever scanned your website using SecurityHeaders.com, you’ve seen the letter grade — A+ through F — based on which HTTP security headers your site is serving. It’s been the go-to tool for quick security header checks since 2014.
In June 2025, Snyk acquired Probely, the company that had absorbed SecurityHeaders.com. In January 2026, Snyk announced the SecurityHeaders.com API is being discontinued in April 2026. If you used the API to automate security header checks in your CI/CD pipeline, monitoring workflow, or internal tooling — that integration stops working next month.
This guide explains what’s changing, who’s affected, and what continuous security header monitoring looks like as an alternative.
What’s covered
- What SecurityHeaders.com does well
- What’s actually shutting down
- The difference between scanning and monitoring
- What continuous security header monitoring checks
- How Guardr compares
- The security grade explained
- Fix instructions included
- Free scanner — no login required
What SecurityHeaders.com does well
To be clear: SecurityHeaders.com is genuinely good at what it does. Paste a URL, get a letter grade, see exactly which headers are missing or misconfigured. It’s fast, free, and the grading methodology is trusted across the industry.
If you just need a one-time check on a single URL and don’t need monitoring, history, or alerts — the free web scanner is still available at securityheaders.com and will continue to work for the foreseeable future.
What’s actually shutting down
The API is shutting down in April 2026 — not the web interface. But the API is what made SecurityHeaders.com useful for anything beyond a manual spot check.
Developers have used the SecurityHeaders.com API to run automated checks after deployments, build internal security dashboards, monitor header configuration in CI/CD pipelines, and trigger alerts when grades drop.
All of that stops working in April. The web scanner stays up, but you can’t automate against it.
The difference between scanning and monitoring
SecurityHeaders.com is a scanner. You initiate a check manually, it returns a result. There is no scheduling, no history, no alerting — you have to remember to go back and check.
Monitoring is different. A monitor checks your site on a schedule — every hour, every day — and alerts you when something changes. If a deployment accidentally removes your Content Security Policy, a monitor catches it within the hour. A scanner catches it whenever you remember to run it manually.
For production sites, client sites, or anything with real users, a scan you have to remember to run isn’t monitoring. It’s a spot check.
The practical gap: SecurityHeaders.com would not have told you the morning a misconfigured deployment wiped your HSTS header. A monitor would have.
What continuous security header monitoring checks
A comprehensive security header monitor should cover more than just headers. Here’s what matters:
Security headers CSP (Content-Security-Policy), HSTS (Strict-Transport-Security), X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy. Missing or misconfigured headers lower your security grade and should trigger an alert when they change.
TLS and SSL certificate expiry Your certificate expiry date, tracked and alerted at 30 days and 7 days before it lapses. A surprise SSL expiry takes your site offline and destroys user trust — it’s one of the most avoidable incidents in web operations.
DNS security DNSSEC validation and CAA record presence, checked via DNS-over-HTTPS. Missing DNS security records are a common oversight that leaves domains vulnerable to hijacking.
Cookie security
Cookies missing the Secure, HttpOnly, or SameSite attributes are a frequent finding on sites that have grown over time without a systematic security review.
Exposure paths
Common sensitive paths probed for accidental exposure: /.git/, /.env, /phpinfo.php, /wp-login.php, /adminer.php. An exposed .git directory can leak your entire source code — and it’s more common than you’d think.
Guardr also scans live JavaScript bundles for exposed API keys (OpenAI, Stripe, AWS, Anthropic, Google AI, Supabase) — checking what’s deployed in production, not just your repository.
Uptime Standard HTTP/HTTPS availability checks every 1–5 minutes. Security and uptime belong in the same dashboard — both affect your users, both need alerts.
How Guardr compares
| SecurityHeaders.com | Guardr | |
|---|---|---|
| Security header scanning | ✅ One-time | ✅ Continuous (hourly on paid) |
| Letter grade (A–F) | ✅ | ✅ |
| Uptime monitoring | ❌ | ✅ |
| Automatic alerts | ❌ | ✅ Email, Slack |
| Grade drop alerts | ❌ | ✅ Paid plans |
| SSL certificate monitoring | ❌ | ✅ 30d and 7d alerts |
| DNS security (DNSSEC/CAA) | ❌ | ✅ |
| Cookie security checks | ❌ | ✅ |
| Exposure path detection | ❌ | ✅ (.git, .env, wp-login) |
| JS secret scanning | ❌ | ✅ (live bundles) |
| Fix instructions per platform | Partial | ✅ Cloudflare, Nginx, Apache |
| Scan history and trends | ❌ | ✅ |
| API access | ⛔ Shutting down April 2026 | ✅ Paid plans |
| Free tier | ✅ | ✅ |
| Paid monitoring | ❌ | ✅ From $7/month |
The security grade explained
Like SecurityHeaders.com, Guardr assigns your site a letter grade from A to F based on its security configuration. The scoring reflects a broader set of checks than headers alone:
- TLS/HSTS: 28%
- Security headers: 28%
- Exposure paths: 20%
- Cookie security: 14%
- DNS security: 10%
Your grade is tracked over time in your dashboard. If a deployment causes it to drop — missing CSP after a framework update, HSTS accidentally removed — you’ll see it in the history and get an alert before it becomes a problem.
Fix instructions included
Every failing check includes platform-specific fix instructions. Not just “your CSP header is missing” — but the exact configuration snippet for Cloudflare Workers, Nginx, or Apache. The goal is to go from finding to fix without opening a second browser tab.
For example, a missing HSTS finding shows you exactly what to add to your _headers file on Cloudflare Pages, your server block on Nginx, or your VirtualHost on Apache. The same pattern applies to every finding in the scanner.
Free scanner — no login required
Not ready to sign up? Scan any URL instantly at guardr.io — no account required. You’ll get a letter grade, a breakdown of every finding, and fix instructions for each issue.
The difference from SecurityHeaders.com: after you see your results, you can start monitoring that URL automatically with one click. No manual checks, no forgetting to come back — your security grade stays current without any effort.
If you’re looking for a direct replacement for the SecurityHeaders.com web scanner, the free tool at guardr.io works the same way.
If you used the API and need to automate security header checks going forward, Guardr’s paid plans include API access alongside continuous monitoring, uptime checks, and alerts.