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 - 93: Not supported
  3. 94: Not supported

Firefox

  1. 2: Not supported (but has polyfill available)
  2. 3: Partial support
  3. 3.5 - 83: Supported
  4. 84 - 92: Not supported
  5. 93: Not supported
  6. 94 - 95: Not supported

Chrome

  1. 4 - 84: Supported
  2. 85 - 93: Not supported
  3. 94: Not supported
  4. 95 - 97: Not supported

Safari

  1. 3.1 - 3.2: Not supported (but has polyfill available)
  2. 4 - 14.1: Supported
  3. 15: Supported
  4. TP: Supported

Opera

  1. 9 - 9.6: Not supported
  2. 10 - 10.5: Not supported (but has polyfill available)
  3. 10.6 - 72: Supported
  4. 73 - 79: Not supported
  5. 80: Not supported

Safari on iOS

  1. 3.2 - 14.8: Supported
  2. 15: Supported

Opera Mini

  1. all: Not supported

Android Browser

  1. 2.1 - 4.4.4: Supported
  2. 94: Not supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 12.1: Supported
  3. 64: Not supported

Chrome for Android

  1. 94: Not supported

Firefox for Android

  1. 92: Not supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 14.0: Supported
  2. 15.0: 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