I'm interested in what applications people use, maybe I can discover some better alternatives.

Music: Spotify for streaming, Dopamine for local music.

Cloud: OneDrive. As a student, I get 1 TB of space for free.

Email: Mailspring, though I'm eyeing eM Client as an alternative right now.

Text Processors: Mostly VS Code with LaTeX, but I do sometimes use good old MS Office.

Code: VS Code again, and also IntelliJ IDEA and CLion for the respective languages. VS Code for anything that isn't C or Java related. I'm also watching the development of Oni Vim 2.

PDF: On my laptop with a touch display, I use Drawboard. On my PC at home I use Nitro PDF.

Browser: Firefox, ever since the quantum update it's nice and snappy. Though maybe I'd switch to Vivaldi when they add Sync at some point.

What are some apps that you use that aren't particularly well known? Let's help each other discover some interesting new tools!

lichess - best chess app out there IMO. Completely free and open source, has daily puzzles, and a pretty active pool of users to play against!
Syncthing - file syncing tool that works with just about any operating system (although I don't think it works with iOS). I use it to take notes and write lyrics/my journal and sync them back to my linux laptop.
Untappd - social media app for tracking craft beers that you drink. I've only just started using it, since I was on holiday and wanted to keep a note of the ales I was drinking. It's a free app, but supported by ads. I believe there's a paid tier, but the free version works well enough, and it's useful for encouraging me and my friends to try new beers when we're out and about.
WK - Japanese flashcard app, which is technically a front-end for the wanikani service. As you learn new radicals, characters, and vocabulary, it serves them back up to you after a certain length of time. If you remember it, it'll wait longer next time, and if you don't get it right, it brings it back to the top of the pile.