• Thumb-Key — A flick keyboard for mobile phones; a FOSS alternative to MessagEase created by Lemmy's own Dessalines. It's not perfect, neither was MessagEase, but for what it is it's pretty damn good and definitely beats using a mobile QWERTY keyboard.
• Ibis — A federated wiki created by Lemmy's own Nutomic. It's currently pretty barebones with little activity, but I'd like to see more interest in the project so that it can grow and improve. I think it has a lot of potential.

Gnu Guix. By default Guix uses only free libre software, but there are ways to install it with a non-free kernal. Systemcrafters has a guide (this is what I used) as well as non-guix (guix repo for non free software).

Thanks for making me feel like an idiot for not knowing things after age 30.

I am surprised that no one mentions this.

Firefly III this is an amazing financial tracking and budgeting tool that literally saves me so much time and money, I even donate monthly since it's so good and essential to me that I think it's only fair that the developer gets something back.

Helix is a modal text editor, but I haven't used it as much as I'd like because it lacks the plugins I use in Neovim.

A more private and secure messenger than WhatsApp, signal and telegram, like simplex

Vorta is a great program for backing up files. Works on Windows, Mac, and Linux.

linux

Couple I've come across recently and haven't seen here yet:

micro - a nano-style terminal text editor with modern features and plugins.

termscp - a terminal FTP (et al) client heavily inspired by WinSCP.

Typst, Nix, Git, Blender

MusicBrainz Picard

Amazing music tagger and batch renamer, for those of us who still have all our music as files.

xpra: it is like tmux but for X windows (works on wayland), but it can do much more than that. You can seamlessly run GUI programs from a container or VM on your main desktop while still sandboxing their X capabilities, forward windows from Windows desktops, and it has efficient encoding so it is usable over poor connections as well.

For 3D Modelling / Printing, if you have even a little bit of programming / scripting ability, OpenSCAD is amazing.

It's basically just a small scripting language for generating 3D objects and performing 3D modelling operations and its so handy to be able to store important info as precise variables, and create new objects and cuts and stuff just with for loops and if statements.

I use the web version a lot of the time, and while it could use a little work, it's pretty amazing.

Shutter encoder, it has a ton of useful tools built in for quick video conversion, compression, trimming, etc, and it works very well for batch encoding of a lot of different video files

Affine, its a surprisingly feature rich notes app (open source but all cloud features are currently paid)

KopiaUI, an easy to use automatic backup program

ViMusic, android APK to play music from youtube, Ive just come across it when I wanted to listen to some OST that were only on youtube and my phone by default doesn't let me play youtube and block the screen. Im not gonna pay any subscriptions ever.

More people should code Csound. Doesn't matter if you're musically inclined or not. Just do it. Make weird noises. Have fun!

• Scrambled EXIF - the simplest upgrade to removing meta data from your photos, when you want to send them to people
• FFShare - the simplest upgrade to removing metadata from your photos/videos AND compressing them when you send or share them with someone. This saves on upload time (upload speeds are often horrible) and bandwidth for both sender and receiver.
• Saber - handwriting notes app for Android
• DiskUsage - disk space analyser and visualiser, with nothing better IMHO
• RootlessJamesDSP - want systemwide Viper4Android but without rooting? This thing needs you to have a degree in audio engineering (lol jk). AutoEQ presets, DSP, convolver, virtual room effects, a crazy equaliser, +15 dB volume gain, its got a bunch of stuff you can customise separately for your phone speakers, different headphones and other connected audio gear.

(yes I might eventually have a long list to update the smartphone guide with solid recommendations)