tabindex global attribute

- LS

Specifies the focusability of the element and in what order (if any) it should become focused (relative to other elements) when "tabbing" through the document.

Chrome

  1. 4 - 14: Support unknown
  2. 15 - 107: Supported
  3. 108: Supported
  4. 109 - 111: Supported

Edge

  1. 12 - 106: Supported
  2. 107: Supported

Safari

  1. 3.1 - 5: Support unknown
  2. 5.1 - 16.0: Supported
  3. 16.1: Supported
  4. 16.2 - TP: Supported

Firefox

  1. 2 - 3.6: Support unknown
  2. 4 - 106: Supported
  3. 107: Supported
  4. 108 - 109: Supported

Opera

  1. 9: Support unknown
  2. 9.5 - 91: Supported
  3. 92: Supported

IE

  1. 5.5 - 6: Support unknown
  2. 7 - 10: Supported
  3. 11: Supported

Chrome for Android

  1. 107: Supported

Safari on iOS

  1. 3.2 - 16.0: Supported
  2. 16.1: Supported

Samsung Internet

  1. 4 - 18.0: Support unknown
  2. 19.0: Support unknown

Opera Mini

  1. all: Support unknown

Opera Mobile

  1. 10 - 12.1: Support unknown
  2. 72: Supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4.4.4: Support unknown
  2. 107: Support unknown

Firefox for Android

  1. 106: Supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Supported

KaiOS Browser

  1. 2.5: Supported

Mac OS X "Full Keyboard Access" refers to setting Keyboard→Shortcuts→Full Keyboard Access to "All controls" in the System Preferences.

"Unknown" support for mobile browsers is due to lacking a method of tabbing through fields.

Resources:
MDN Web Docs - tabindex attribute