Search Engines Helper от Soufiane Sakhi

This extensions provides multiple utilities for firefox search engines.
You can add a new custom search engine using the context menu or by providing the search url and the icon url.
You can also export the search url and icon urls of all the search engines added to Firefox and import them later.

For more details, visit the full documentation here: https://github.com/soufianesakhi/firefox-search-engines-helper/blob/master/README.md