Heynote is great. It scratches an itch I've had for a while for a lightweight scratchpad-ey note system.
- It can save notes in a cloud drive, so you can sync stuff
- It's txt file native, but can handle markdown and many other code formats
- It lets you easily create new "blocks" to have a little bit of hierarchy within note files, but it doesn't go crazy with hierarchy the way Logseq, Obsidian, and other tools allow you to.
- It can evaluate math expressions, which is really nice
It's feels rare to find little tools like this that so perfectly hit the Goldilocks zone for what I want them to be.