The markdown-based note-taking app that doesn't suck.

I couldn't find a note-taking app that ticked all the boxes I'm interested in: notes are written and rendered in GitHub-flavored Markdown, no WYSIWYG, no proprietary formats, I can run a search & replace across all notes, notes support attachments, the app isn't bloated, the app has a pretty interface, tags are indefinitely nestable and can import Evernote notes (because that's what I was using before).

So I built my own.