[progman32]

Not op, but if you go to kagi.com and look in the search bar (edit: Firefox's own built in search bar) you'll see a little green plus over the magnifying glass. Click it and you'll see an option to add it to the search engine list.

[Daffodils]

Just to add to this, in firefox, you can use the extension "Add custom search engine"[1] and you can add any search engine to your firefox search engine list, and to the address bar. Another benefit of using this, you can access your saved preferences while searching from the address bar. DDG, Startpage, Kagi all give you a bookmarklet URL which you can add through this extension.

[1] https://addons.mozilla.org/en-US/firefox/addon/add-custom-se...

[the-dude]

Thank you!