# Application Search Engines

Firefox defines various application search engines that are shipped to users.

The extensions for the definitions of these engines live in
{searchfox}`browser/components/search/extensions <browser/components/search/extensions>`

## Icons

### Icon Requirements

It is preferred that each engine is shipped with a `.ico` file with two sizes
of image contained within the file:

- 16 x 16 pixels
- 32 x 32 pixels

Some engines also have icons in
{searchfox}`browser/components/topsites/content/tippytop <browser/components/topsites/content/tippytop>`.
For these engines, there are two sizes depending on the subdirectory:

- `favicons/`: 32 x 32 pixels
- `images/`: preferred minimum of 192 x 192 pixels

### Updating Icons

To update icons for application search engines:

- Place the new icon file in the {searchfox}`folder associated with the search engine <browser/components/search/extensions>`.
- Increase the version number in the associated manifest file. This ensures
  that the add-on manager properly updates the engine.
- Be aware that the {searchfox}`allowed-dupes.mn file <browser/installer/allowed-dupes.mn>`
  lists some icons that are intended as duplicates.

To update icons for tippytop:

- Place the new icon file in {searchfox}`both the sub-folders within the tippytop directory <browser/components/topsites/content/tippytop>`.
