CSS zoom

- UNOFF

Non-standard method of scaling content.

IE

  1. 5.5 - 7: Supported
  2. 8 - 10: Supported
  3. 11: Supported

Edge

  1. 12 - 93: Supported
  2. 94: Supported

Firefox

  1. 2 - 92: Not supported
  2. 93: Not supported
  3. 94 - 95: Not supported

Chrome

  1. 4 - 93: Supported
  2. 94: Supported
  3. 95 - 97: Supported

Safari

  1. 3.1 - 3.2: Not supported
  2. 4 - 14.1: Supported
  3. 15: Supported
  4. TP: Supported

Opera

  1. 9 - 12.1: Not supported
  2. 15 - 79: Supported
  3. 80: Supported

Safari on iOS

  1. 3.2: Not supported
  2. 4 - 14.8: Supported
  3. 15: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 94: Supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 64: Supported

Chrome for Android

  1. 94: Supported

Firefox for Android

  1. 92: Not supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 14.0: Supported
  2. 15.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Not supported

Originally implemented only in Internet Explorer. Although several other browsers support the property, using transform: scale() is the recommended solution to scale content. Note though that transform: scale() does not work the same as zoom. If e.g. transform: scale(0.6) is used on the html or body element then it resizes the entire page, showing a minified page with huge white margins around it, whereas zoom: 0.6 scales the elements on the page, but not the page itself on which the elements are drawn.

Resources:
Article explaining usage of zoom as the hack for fixing rendering bugs in IE6 and IE7.
CSS Tricks
Safari Developer Library
MDN Web Docs - CSS zoom
WebPlatform Docs