JotDown is a markdown-based note-taking and organizing app. 

It supports the usual array of markdown features, plus: 

•  Organizing your documents by directory, category, and tag, with all metadata stored in the document itself, as standard YAML
• (optional) progressive screenshake effect for typing streaks
• Checkbox syncing between the document and markdown preview
• Flow charts and sequence diagrams
• Distraction free and typewriter modes

https://billiam.itch.io/jotdown