No other file is as widely openable as a “.txt”.
For notetaking, anything other than fleeting notes should be entered into a future-proof system. The most future-proof system of all is plain text.
Plain text is durable. This king of the Durable File Types. Tools may come and go, but every tool can work with plain text. They are the most widely openable file format in existence. You can open plain text files (and their semantic offshoots, like Markdown files) in almost anything. Even the console itself can display them.
Tools like the Notetaking platform “Obsidian” were built around plain text files for this very reason. However all of them come with some non-standard features that wouldn’t simply and natively migrate to other systems without some work. For example Obsidian’s syntax for alias references using the pipe character would need to be stripped if you were to build a DIY app.
Extending “Plain” Text
- For formatting, you can utilize Markdown.
- Data can be stored via CSV, JSON, YAML, or XML.
- Graphics can be stored using ASCII Art, or (with minimal risk) the source code for open-source Diagrams as Code platforms, such as Mermaid.
- Similarly, other Open Source formats that allow for UTF-8 formatting exports would have a decent chance of survival - such as Excalidraw and DrawIO.