Can I use
?

SPDY protocol

- UNOFF

Networking protocol for low-latency transport of content over the web. Superseded by HTTP version 2.

Chrome

  1. ✅ 4 - 50: Supported
  2. ❌ 51 - 127: Not supported
  3. ❌ 128: Not supported
  4. ❌ 129 - 131: Not supported

Edge

  1. ❌ 12 - 127: Not supported
  2. ❌ 128: Not supported

Safari

  1. ❌ 3.1 - 7.1: Not supported
  2. ✅ 8 - 12: Supported
  3. ✅ 12.1 - 17.5: Supported
  4. ✅ 17.6: Supported
  5. ✅ 18.0 - TP: Supported

Firefox

  1. ❌ 2 - 12: Not supported
  2. ✅ 13 - 50: Supported
  3. ❌ 51 - 129: Not supported
  4. ❌ 130: Not supported
  5. ❌ 131 - 133: Not supported

Opera

  1. ❌ 9 - 12: Not supported
  2. ✅ 12.1 - 39: Supported
  3. ❌ 40 - 41: Not supported
  4. ✅ 42: Supported
  5. ❌ 43: Not supported
  6. ✅ 44: Supported
  7. ❌ 45 - 110: Not supported
  8. ❌ 111: Not supported

IE

  1. ❌ 5.5 - 10: Not supported
  2. ✅ 11: Supported

Chrome for Android

  1. ❌ 128: Not supported

Safari on iOS

  1. ❌ 3.2 - 7.1: Not supported
  2. ✅ 8 - 12.1: Supported
  3. ✅ 12.2 - 17.5: Supported
  4. ✅ 17.6: Supported
  5. ✅ 18.0: Supported

Samsung Internet

  1. ✅ 4: Supported
  2. ❌ 5 - 24: Not supported
  3. ❌ 25: Not supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ❌ 10 - 12: Not supported
  2. ✅ 12.1: Supported
  3. ❌ 80: Not supported

UC Browser for Android

  1. ❌ 15.5: Not supported

Android Browser

  1. ❌ 2.1 - 2.3: Not supported
  2. ✅ 3 - 4.4.4: Supported
  3. ❌ 128: Not supported

Firefox for Android

  1. ❌ 127: Not supported

QQ Browser

  1. ❌ 14.9: Not supported

Baidu Browser

  1. ❌ 13.52: Not supported

KaiOS Browser

  1. ✅ 2.5: Supported
  2. ❌ 3: Not supported

See also support for HTTP2, successor of SPDY.

Resources:
SPDY whitepaper
Wikipedia