PNG alpha transparency

- REC

Semi-transparent areas in PNG files

IE

  1. 5.5
  2. 6
  3. 7 - 10
  4. 11

Edge

  1. 12 - 81
  2. 83

Firefox

  1. 2 - 75
  2. 76
  3. 77 - 78

Chrome

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

Safari

  1. 3.1 - 13
  2. 13.1
  3. TP

Opera

  1. 9 - 67
  2. 68

iOS Safari

  1. 3.2 - 13.3
  2. 13.4

Opera Mini

  1. all

Android Browser

  1. 2.1 - 4.4.4
  2. 81

Blackberry Browser

  1. 7
  2. 10

Opera Mobile

  1. 10 - 12.1
  2. 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

IE6 does support full transparency in 8-bit PNGs, which can sometimes be an alternative to 24-bit PNGs.

Resources:
Workaround for IE6
Wikipedia