HSTS Check

Check the presence of the Strict-Transport-Security header and its status in the Chrome preload list.

Enter a domain — the service will make an HTTPS request and inspect the response headers.

HSTS Check Online

The HSTS Check tool on 101IP verifies the presence of the Strict-Transport-Security header on your site and analyses its parameters: lifetime, subdomain coverage and the preload directive. It also checks the domain's status in the Chrome HSTS Preload List.

What is HSTS

HTTP Strict Transport Security (HSTS) is a mechanism that forces the browser to always connect to a site over HTTPS, even if the user types the address without a protocol. It protects against SSL stripping attacks.

Chrome preload list requirements

Valid HTTPS certificate without errors;
HTTP to HTTPS redirect;
max-age of at least 31,536,000 seconds (1 year);
The includeSubDomains directive;
The preload directive.