For me, Google video search, Google books (Internet Archive is good, but doesn’t always have the same stuff), Adobe InDesign (but in the process of learning LaTeX), and Typewise. As for the Google stuff, I liked Whoogle a lot, but almost all their instances seem to have been blocked or shut down. Also, apologies if this is repeating an earlier post.
Most of the times -for me anyway- not only are the tools free (as in freedom) and free (as in beer) but also simply vastly superior to paid alternatives. I never get why people pay and then put up with shit, or use some SaaS platform where they are the product and get spied on and still put up with so much shit that they would be double better off by switching to something open