HTTP Strict Transport Security (HSTS) is a security header standard that instructs browsers to only ever connect to a site over HTTPS, protecting against protocol-downgrade and cookie-hijacking attacks on the first request. Our engine detects it through 1 HTTP header check for the `Strict-Transport-Security` response header. Like CSP, this is a security-configuration signal we surface alongside builder/technology detection, not a vendor or platform identification. Reference: MDN's HSTS documentation.
Detect HSTS Websites — Free Tool
Enter any URL to check if it was built with HSTS. Instant results, no account required.
How we detect HSTS — see our methodology: AI Influence Score calculation, evidence tiers, and fingerprint signal types.
How to Detect HSTS Websites
HTTP Headers
1 patterns
1. Check the Page Source
Open the website in your browser, right-click, and select "View Page Source". Search for hsts-specific patterns in the HTML.
4. Use AI Website Detector (Easiest)
Our automated scanner checks all these signals at once and gives you an instant confidence score. Just enter any URL above.
Frequently Asked Questions
Is this website built with HSTS?
You can detect if any website was built with HSTS by using our free scanner above. Just enter the URL and we'll analyze HTML patterns, JavaScript files, CDN domains, and HTTP headers to determine if HSTS was used — with a confidence score.
How to detect if a website was built with HSTS?
There are several ways to detect HSTS: (1) View the page source and look for HSTS-specific class names or script URLs, (2) Check the Network tab in DevTools for requests to HSTS CDN domains, (3) Use our free tool — we check 1 detection signals automatically.
What websites are built with HSTS?
HSTS is used by thousands of websites worldwide. Our scanner has detected many HSTS-built sites across different industries. You can scan any URL to check if it uses HSTS.
How accurate is the HSTS detection?
Our HSTS detection engine checks 1 unique fingerprint signals, achieving high confidence results. We score each match and return a confidence percentage so you know how certain the detection is.
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Detection Info
- Category
- Security
- Signals Used
- 1 patterns
- Accuracy
- High
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