Can I use
?

Offline web applications

- UNOFF

Now deprecated method of defining web page files to be cached using a cache manifest file, allowing them to work offline on subsequent visits to the page.

IE

  1. 5.5: Not supported
  2. 6 - 8: Not supported (but has polyfill available)
  3. 9: Not supported
  4. 10: Supported
  5. 11: Supported

Edge

  1. 12 - 84: Supported
  2. 85 - 86: Not supported
  3. 87: Not supported

Firefox

  1. 2: Not supported (but has polyfill available)
  2. 3: Partial support
  3. 3.5 - 83: Supported
  4. 84: Not supported
  5. 85 - 86: Not supported

Chrome

  1. 4 - 84: Supported
  2. 85 - 86: Not supported
  3. 87: Not supported
  4. 88 - 90: Not supported

Safari

  1. 3.1 - 3.2: Not supported (but has polyfill available)
  2. 4 - 13.1: Supported
  3. 14: Supported
  4. TP: Supported

Opera

  1. 9 - 9.6: Not supported
  2. 10 - 10.5: Not supported (but has polyfill available)
  3. 10.6 - 71: Supported
  4. 72: Supported

iOS Safari

  1. 3.2 - 13.7: Supported
  2. 14: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 81: Not supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 12.1: Supported
  3. 59: Supported

Chrome for Android

  1. 87: Not supported

Firefox for Android

  1. 83: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 12.0: Supported
  2. 13.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Supported

This technology is being deprecated in favor of Service Workers

Resources:
Dive Into HTML5 article
Mozilla Hacks article/demo
Sitepoint tutorial
WebPlatform Docs