If you are experiencing issues, check https://github.com/ssborbis/ContextSearch-web-ext/releases for signed pre-releases with the latest fixes ContextSearch web-ext The most powerful, most complete search enhancement for Firefox This Add-on was written as a Firefox 57+ web-extensions compatible replacement for Ben Basson's popular Context Search Add-on but has grown into much more.

Import your currently installed search engines
Access search engines from the Context Menu
Manage search engines using subfolders and separators
Access search engines from a popup menu (QuickMenu)
Compatible with all search engines using POST or GET requests
International character-set support
Reverse-image search
Site search
Add new search engines simply with a right-click
Custom API to build and install custom OpenSearch engines to FIrefox Search Toolbar
Edit search engine parameters and icons
Access bookmarklets from the context menu and quick menu
Highlight search terms
Lite and Dark themes
Use custom CSS for menus

* Linux and MacOS X users may need to set the option ui.context_menus.after_mouseup to true in about:config for mouse actions to work properly Permissions <all_urls> This addon is works on all websites activeTab This addon injects code into tabs to create menus and styling contextMenus This addon provides a context menu search This addon interacts with Firefox search engines storage This addon saves preferences tabs This addon provides means to open search results in new tabs and windows More info @ https://github.com/ssborbis/ContextSearch-web-ext