Web Sockets

- LS

Bidirectional communication technology for web apps

IE

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

Edge

  1. 12 - 79: Supported
  2. 80: Supported

Firefox

  1. 2 - 3.6: Not supported
  2. 4 - 5: Partial support
  3. 6 - 10: Partial support
  4. 11 - 72: Supported
  5. 73: Supported
  6. 74 - 75: Supported

Chrome

  1. 4 - 14: Partial support
  2. 15: Partial support
  3. 16 - 79: Supported
  4. 80: Supported
  5. 81 - 83: Supported

Safari

  1. 3.1 - 4: Not supported
  2. 5 - 5.1: Partial support
  3. 6 - 6.1: Partial support
  4. 7 - 12.1: Supported
  5. 13: Supported
  6. TP: Supported

Opera

  1. 9 - 10.6: Not supported
  2. 11 - 12: Partial support
  3. 12.1 - 65: Supported
  4. 66: Supported

iOS Safari

  1. 3.2 - 4.1: Not supported
  2. 4.2 - 5.1: Partial support
  3. 6 - 13.1: Supported
  4. 13.2: Supported
  5. 13.3: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.3: Not supported
  2. 4.4 - 4.4.4: Supported
  3. 80: Supported

Blackberry Browser

  1. 7: Supported
  2. 10: Supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 12: Partial support
  3. 12.1: Supported
  4. 46: Supported

Chrome for Android

  1. 80: Supported

Firefox for Android

  1. 68: Supported

IE Mobile

  1. 10: Supported
  2. 11: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 9.2: Supported
  2. 10.1: Supported

QQ Browser

  1. 1.2: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

Reported to be supported in some Android 4.x browsers, including Sony Xperia S, Sony TX and HTC.

Resources:
Details on newer protocol
WebSockets information
MDN Web Docs - WebSockets API
Wikipedia
has.js test
WebPlatform Docs