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HTTP Strict Transport Security

(also HSTS)

HTTP Strict Transport Security definition

HTTP Strict Transport Security (HSTS) operates as a web safety policy tool, safeguarding websites from a range of cyber threats, such as protocol downgrade assaults and cookie theft. It confirms that the user's browser establishes a connection with the website solely via a secure HTTPS pathway and never through an unsecured HTTP route.

See also: SSL encryption, transport layer

HTTP Strict Transport Security examples

  • Website protection: HSTS is implemented by websites to ensure user interactions occur only over secure HTTPS, mitigating the risks of man-in-the-middle attacks.
  • Browser compliance: Most modern web browsers, including Chrome, Firefox, and Safari, support HSTS to reinforce user data safety during online activities.

Advantages and disadvantages of HTTP Strict Transport Security


  • Security enhancement: HSTS significantly boosts web security by enforcing HTTPS encryption, shielding against downgrade attacks and cookie hijacking.
  • Automatic HTTPS redirection: It reduces the need for manual redirects by automatically switching HTTP requests to HTTPS.


  • Initial connection risk: The first connection to a website is not protected by HSTS, exposing it to potential attacks. This risk is mitigated with HSTS preload lists.
  • Website inaccessibility: If the SSL certificate of a website using HSTS expires or is misconfigured, the website becomes inaccessible until the issue is resolved.

Using HTTP Strict Transport Security

  • Web developers should implement HSTS as part of their website security setup to enhance user data protection.
  • Browser users should keep their browsers updated to ensure HSTS compliance.