Lofi is a mini Spotify player with visualizations. It is not a replacement for the Spotify Desktop app, nor does it play music independently of the Spotify app; instead, Lofi works alongside it to provide a more intuitive and pleasant access to common features. Lofi also displays cover art and track info stylishly and it facilitates WebGL-powered audio visualizations for both Windows, MacOS and Linux. In other words, it's a "tiny Spotify player" or a "mini mode" to enhance the Spotify desktop app.

fediverse.space is a tool to visualize networks and communities on the fediverse. It works by scraping every instance it can find and aggregating statistics on communication between these.

KeyCastr, an open-source keystroke visualizer.

pixd is a tool for visualizing binary data using a colour palette. It is in a lot of ways akin to a hexdump tool, except using coloured squares to represent each octet.