Royalty-free open audio codec by IETF, which incorporated SILK from Skype and CELT from Xiph.org, to serve higher sound quality and lower latency at the same bitrate.

IE

  1. 5.5 - 10: Not supported
  2. 11: Not supported

Edge

  1. 12 - 13: Not supported
  2. 14 - 79: Supported
  3. 80: Supported

Firefox

  1. 2 - 14: Not supported
  2. 15 - 73: Supported
  3. 74: Supported
  4. 75 - 76: Supported

Chrome

  1. 4 - 32: Not supported
  2. 33 - 79: Supported
  3. 80: Supported
  4. 81 - 83: Supported

Safari

  1. 3.1 - 10.1: Not supported
  2. 11 - 12.1: Partial support
  3. 13: Partial support
  4. 13.1 - TP: Partial support

Opera

  1. 9 - 19: Not supported
  2. 20 - 65: Supported
  3. 66: Supported

iOS Safari

  1. 3.2 - 10.3: Not supported
  2. 11 - 13.2: Partial support
  3. 13.3: Partial support
  4. 13.4: Partial support

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Not supported
  2. 80: Not supported

Blackberry Browser

  1. 7: Not supported
  2. 10: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 46: Not supported

Chrome for Android

  1. 80: Supported

Firefox for Android

  1. 68: Supported

IE Mobile

  1. 10: Not supported
  2. 11: Not supported

UC Browser for Android

  1. 12.12: Not supported

Samsung Internet

  1. 4: Not supported
  2. 5 - 10.1: Supported
  3. 11.1: Supported

QQ Browser

  1. 1.2: Not supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

Support refers to this format's use in the audio element, not other conditions.

For Opera the Linux version may be able to play it when the GStreamer module is up to date and the served mime-type is 'audio/ogg'.

Resources:
Google's statement about the use of VP8 and Opus codec for WebRTC standard
Introduction of Opus by Mozilla
Microsoft Edge feature request on UserVoice