Chafa - I can turn pictures in ANSI art for my terminal
Syncthing - A godsend for me and I can't believe how easy it is to set up and have it just work, I was almost disappointed when I was setting it up expecting issues and then the mf just works perfectly fine without issue
Tailscale - Very useful to remotely ssh to my computer(s) even from my phone
Termux - terminal on android
This one you may have heard of and it's not exactly niche, indie or small but I'll add it anyways just in case:
Too Good To Go - allows you to get cheap food and save it from going to waste. I use it a lot when I can't go to the university cafeteria and don't feel like cooking