This is a bit late, but a few months ago I discovered Obsidian. (on 03/16/2024)
An incredibly powerful tool for taking notes and organizing things.
The problem:
In the last few years, I've gone into the habit of taking notes of a lot of things, but didn't know where to put them. So quite a few folders of mine had at least a couple of text files in them for notes I had related to whatever that folder was about.
But eventually I got into a problem where I had tons of small notes spread about random folders everywhere.
And often times I wanted to remember something I knew I had taken notes of, but I didn't know in what folder I put those notes in, which made those notes pointless.
The solution:
That's when I discovered Obsidian
Obsidian takes note taking to another level.
It functions just like your own local wikipedia, with interlinked notes.

You can create a local database of notes that link between themselves so you can find related notes really fast.
Even if you don't remember exactly where the thing what you want is, as long as you find a note that is related it it, you'll eventually find it.

The notes are just markdown text files.
And the database is just a folder in your computer. So its easy to backup and use.
So I kept making notes of the thing I've learned about, and slowly growing my database of knowledge.
You can even get a nice animated relation graph of your notes being created and linked together.

If Obsidian was only that it would already be a great tool, but it has so much more.
Obsidian has a big community and lots of community plugins that can entirely change of it works, adding new functionality and customizing it to your needs.

One such example is Excalidraw. Its a great plugin that lets you draw shapes and diagrams.
I use it quite a bit to prototype ideas for games. It's easier to use and cleaner than opening a proper painting program. You can save or download a collection of shapes to re-use it later.
And it is also great for making simple class diagrams and save them all in one place.

But that's it.
---
PS: Patreon doesn't allow embeded videos, so I've added the small videos I originally recorded to show here in the attachments.