Free Software that I rely on. One per day.
Day 24:
Firefox
I've been using Mozilla-based browsers since Netscape, and I still do.
And a LOT of my time is spent using the browser, whether socializing on the Fediverse or managing my server.
Despite the current kerfuffle over Mozilla incorporating opt-out AI features that no one wants, I think they are still the best option. Perhaps I'll have to tinker with my settings, or perhaps I'll use one of the several available forks -- but it'll still be Mozilla underneath.
Also, I think it is critical to retain an ecosystem of multiple browsers, rather than a single approved one. We saw the dangers of that with Internet Explorer, and we see it now with Chromium dependencies.
https://www.firefox.com
https://www.mozilla.org
https://firefox-source-docs.mozilla.org/