Over the course of the last year I have been working on building a personal zettlekasten. I started in Notion, making several relational databases. However, after experiencing some down time, I decided to switch to Obsidian (<a href="https://obsidian.md/" rel="nofollow">https://obsidian.md/</a>) it's a much, much better program, does not have slowdown issues on my mac, is fully cross platform (Mac, Windows, Linux) and has a sync system that works pretty seamlessly. Not to mention that the files are all plain markdown and stored locally.