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
  2. 9 - 10
  3. 11

Edge

  1. 12 - 81
  2. 83

Firefox

  1. 2
  2. 3 - 3.6
  3. 4 - 49
  4. 50 - 75
  5. 76
  6. 77 - 78

Chrome

  1. 4
  2. 5 - 81
  3. 83
  4. 84 - 86

Safari

  1. 3.1 - 4
  2. 5
  3. 5.1 - 6.1
  4. 7 - 13
  5. 13.1
  6. TP

Opera

  1. 9 - 10.1
  2. 10.5 - 67
  3. 68

iOS Safari

  1. 3.2
  2. 4 - 13.3
  3. 13.4

Opera Mini

  1. all

Android Browser

  1. 2.1
  2. 2.2 - 4.4.4
  3. 81

Blackberry Browser

  1. 7
  2. 10

Opera Mobile

  1. 10
  2. 11 - 12.1
  3. 46

Chrome for Android

  1. 81

Firefox for Android

  1. 68

IE Mobile

  1. 10
  2. 11

UC Browser for Android

  1. 12.12

Samsung Internet

  1. 4 - 10.1
  2. 11.1

QQ Browser

  1. 10.4

Baidu Browser

  1. 7.12

KaiOS Browser

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