You can search in your open tabs by entering "%" before the search term. It will only search in tab title or URL, but not in page content afaik.

It's similar, but a little more work: You'll notice that you can activate built-in search engines by starting to type their name, and when "Search with [engine]" shows up in the drop-down, you can press Tab. You can test with Bing, DuckDuckGo, etc. But let's say you want to add another site. On some sites (like Startpage), the page has a tag that Firefox auto-detects. In that case, you can right-click the address bar, and add the search engine from the bottom of the context menu. What about sites that do not offer this? Well... You have 3 options: (1) Find an add-on on the Addons site. Let's say you look for ''youtube search'' https://addons.mozilla.org/firefox/search/?q=youtube%20search The problem is figuring out which one is a pure search engine definition versus something with more features. Search engine definition extensions don't require any permissions, so if you need to grant permissions to install, you know it's not what you're looking for. This one has a very thorough explanation of what is does, so this is the one I would try first (if I were looking for this): https://addons.mozilla.org/firefox/addon/youtube-search-engine/ (2) Create your own search engine by hand This is a hidden option that isn't fully baked yet. Last time I tested, there wasn't a way to add an icon, and if you made an error or needed to edit it, you could only delete it and start again. I'll link to a thread with instructions if you want to try it or have it as an option: https://support.mozilla.org/questions/1445232 (3) Create your own search engine using an add-on I haven't used this for a few years, but if you want to try it, it may give nicer results than method #2: https://addons.mozilla.org/firefox/addon/search-engines-helper/