CSS3 Border-radius (rounded corners)

- CR

Method of making the border corners round. Covers support for the shorthand border-radius as well as the long-hand properties (e.g. border-top-left-radius)

IE

  1. 5.5 - 8: Not supported
  2. 9 - 10: Supported
  3. 11: Supported

Edge

  1. 12 - 90: Supported
  2. 91: Supported

Firefox

  1. 2: Partial support
  2. 3 - 3.6: Supported
  3. 4 - 49: Supported
  4. 50 - 88: Supported
  5. 89: Supported
  6. 90 - 91: Supported

Chrome

  1. 4: Supported
  2. 5 - 90: Supported
  3. 91: Supported
  4. 92 - 94: Supported

Safari

  1. 3.1 - 4: Supported
  2. 5: Supported
  3. 5.1 - 6.1: Supported
  4. 7 - 14: Supported
  5. 14.1: Supported
  6. 15 - TP: Supported

Opera

  1. 9 - 10.1: Not supported
  2. 10.5 - 75: Supported
  3. 76: Supported

Safari on iOS

  1. 3.2: Supported
  2. 4 - 14.4: Supported
  3. 14.5: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1: Supported
  2. 2.2 - 4.4.4: Supported
  3. 91: Supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 12.1: Supported
  3. 62: Supported

Chrome for Android

  1. 91: Supported

Firefox for Android

  1. 89: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 13.0: Supported
  2. 14.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported
Resources:
Polyfill which includes border-radius
Border-radius CSS Generator
MDN Web Docs - CSS border-radius
Detailed compliance table
WebPlatform Docs