How to use the HSTS check
HSTS, or HTTP Strict Transport Security, is a security header that tells browsers to use HTTPS for a domain for a defined period. It is not a classic SEO ranking factor, but a coherent HTTPS setup reduces risk, unnecessary redirects and weak configurations that often appear during technical audits, migrations and QA.
What an HSTS checker reviews
The tool checks for Strict-Transport-Security, reads max-age, includeSubDomains and preload, and flags whether the final response is not HTTPS. The header is evaluated on the final response after redirects.
max-age, includeSubDomains and preload
A very low max-age makes HSTS less effective. includeSubDomains extends the policy to subdomains, while preload requires extra care because it can make HTTPS behavior stricter for the whole domain.
Technical SEO and security
For an SEO agency, HSTS belongs in technical checks around HTTPS, HTTP-to-HTTPS redirects, migrations, international domains and subdomains. A clear configuration can also reduce unnecessary redirect chains.
Use it with the redirect checker
First confirm whether HTTP redirects correctly to HTTPS with the redirect checker. Then use the HSTS check to see whether the domain communicates a durable HTTPS policy to browsers.
Related tools
