Tools for Thinking
Obsidian: https://obsidian.md/  - All content stored as flat files on your hard drive.
  - Organised by correctly named folders.
  - Can embed images. Will link or autocopy them to the appropriate folders.
  - Is great if you like markdown.
  - Dark theme.

Honorable mentions:  - Infinite tab indentation synced in google docs, in google drive, since I already pay for google anyway.
  - todo.txt