CSS zoom

- UNOFF

Non-standard method of scaling content.

Chrome

  1. 4 - 124: Supported
  2. 125: Supported
  3. 126 - 128: Supported

Edge

  1. 12 - 123: Supported
  2. 124: Supported

Safari

  1. 3.1 - 3.2: Not supported
  2. 4 - 17.4: Supported
  3. 17.5: Supported
  4. 17.6 - TP: Supported

Firefox

  1. 2 - 125: Not supported
  2. 126: Not supported
  3. 127 - 129: Not supported

Opera

  1. 9 - 12.1: Not supported
  2. 15 - 108: Supported
  3. 109: Supported

IE

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

Chrome for Android

  1. 124: Supported

Safari on iOS

  1. 3.2: Not supported
  2. 4 - 17.4: Supported
  3. 17.5: Supported
  4. 17.6: Supported

Samsung Internet

  1. 4 - 23: Supported
  2. 24: Supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 80: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 124: Supported

Firefox for Android

  1. 125: Not supported

QQ Browser

  1. 14.9: Supported

Baidu Browser

  1. 13.52: Supported

KaiOS Browser

  1. 2.5: Not supported
  2. 3: 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:
CSS Tricks
Safari Developer Library
MDN Web Docs - CSS zoom
Article explaining usage of zoom as the hack for fixing rendering bugs in IE6 and IE7.