As in title, preferably open-source, but doesn’t have to, I will start:
KOReader - Amazing reader app, and being able to use the same app across various devices, even non-android ones, is pure bliss. Japanese support is pretty good too, which makes me happy. Though… Sadly no vertical text support :c
Syncthing-fork - Being able to keep a library of books, and some files, and easily keep the shared folder across various devices, is mega comfy. Tachiyomi - Cute manga reader.
NewPipe - Really pleasant youtube client, that i sometimes use to listen to things in the background.
Kaku - An useful Japanese OCR app, that works… quite decently for when I encounter kanji that I do not recognize, and is not text.
EinkBro - A web browser, that on e-ink devices, is quite comfy. Has few… quirks, but works well on e-ink
Merlin - It’s a birding app and can identify birds by picture or by their song.
Oh how cool though, I didn’t realize they had anything out there that can identify birds by song like that. Is it pretty accurate?
I use BirdNET, I had more luck identifying birds by song than with Merlin. But both are impressive.
Its really good in North America given that it is from Cornell. Gets probably a bird or two wrong out of hundreds
When I’m in India, its a kinda of a swing and a miss, but they’re constantly improving it.
I’ve found auditory ID quite reliable, photo ID is pretty good and questionnaire ID not very.