Browser security
Compatibility & evidence
Transport and response hardening

HTTP Strict Transport Security

Tells supporting browsers to use HTTPS for a host during a declared period.

Support in current browsers

Checked against the current browser versions recorded in MDN browser data 8.1.5.

BrowserMinimumOutcomeReason
Chrome155WorksEvery required mapped BCD feature is available without a recorded qualification.
Edge154WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox157WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari27WorksEvery required mapped BCD feature is available without a recorded qualification.
Chrome for Android155WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox for Android157WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari on iOS27WorksEvery required mapped BCD feature is available without a recorded qualification.
Android WebView155WorksEvery required mapped BCD feature is available without a recorded qualification.
Samsung Internet30.0WorksEvery required mapped BCD feature is available without a recorded qualification.
The release trace

How support changed

Each segment groups recorded releases with the same result. Gaps between recorded versions are not filled in. This is support at each release, rather than the planner’s check of every release above a minimum.

Chrome

http.headers.Strict-Transport-Security
  1. 1 – 33 recorded releases
    Not supported
  2. 4 – 155151 recorded releases
    Works

Edge

http.headers.Strict-Transport-Security
  1. 12 – 15482 recorded releases
    Works

Firefox

http.headers.Strict-Transport-Security
  1. 1 – 3.66 recorded releases
    Not supported
  2. 4 – 157154 recorded releases
    Works

Safari

http.headers.Strict-Transport-Security
  1. 1 – 611 recorded releases
    Not supported
  2. 7 – 2750 recorded releases
    Works

Chrome for Android

http.headers.Strict-Transport-Security
  1. 18 – 155131 recorded releases
    Works

Firefox for Android

http.headers.Strict-Transport-Security
  1. 4 – 157141 recorded releases
    Works

Safari on iOS

http.headers.Strict-Transport-Security
  1. 1 – 68 recorded releases
    Not supported
  2. 7 – 2750 recorded releases
    Works

Android WebView

http.headers.Strict-Transport-Security
  1. 1 – 46 recorded releases
    Not supported
  2. 4.4 – 155120 recorded releases
    Works

Samsung Internet

http.headers.Strict-Transport-Security
  1. 1.0 – 30.052 recorded releases
    Works

BCD 8.1.5 · catalogue 2.3.0. Source corrections can change this trace without a new browser release.

What this feature can and cannot do

Helps protect against

  • HTTP downgrade
  • Accidental insecure navigation

Does not guarantee

  • First-visit downgrade before policy is known
  • TLS defects
  • Certificate compromise

What you need before using it

  • Reliable HTTPS
  • A carefully chosen host and subdomain policy

Fallback to keep in place

Redirect HTTP to HTTPS and remove insecure links while assessing preload separately.