A fast, native Markdown engine.
For humans and agents.
No Web engine. No plugin system. No account. You open it, you read.
Signed and notarized. Double-click and it opens — no Gatekeeper workaround.
How fast
| MuM |
|---|
| Cold start to window on screen | 280 ms |
| 1 MB document, open to readable | 622 ms |
| 5 MB document, first screen laid out | 302 ms |
| Bundle size | 3 MB |
For humans
- Multi-project —— Several projects open at once, ⌘1…⌘9 to switch. Projects answer “where am I”.
- Made for reading —— Remembers where you were, ⌘F find, document outline, cross-project search.
- Typographic tuning for CJK —— Line height, punctuation, CJK/Latin spacing — all measured, not guessed.
For agents
- Headless rendering ——
mum render --png — the same typesetting engine.
- Structured output —— outline / search emit
--json with meaningful exit codes.