Siren

Write Mermaid diagrams, or Markdown documents with diagrams in them, and see them drawn as you type. Private, and works offline.

Live at https://plwg.github.io/siren/

• Two modes: one Mermaid diagram, or a Markdown document with any number of ```mermaid blocks.
• Share by link or QR code. Your work is compressed into the link; no server ever sees it.
• Export diagrams as SVG, PNG or a copied image, and documents as PDF or .md.
• Private and offline. No accounts or tracking, and shared links can't load images or run scripts.
• Themes: Sail (light), Deep (dark), Lighthouse (high contrast), or Auto.

Rendered by Pele, Marked and highlight.js. See the guide for every feature and how Siren handles untrusted links.

Develop

Requires Bun.

bun install
bun run dev          # local dev server
bun run check        # lint, typecheck, test and build: run before committing
bun run format       # Biome: fix formatting and import order
bun run screenshots  # rebuild the screenshots, link-preview image and touch icon
                     # (first: bunx playwright-core install chromium)

Pushing to main builds and deploys to GitHub Pages via .github/workflows/pages.yml.

License

MIT. Pele, Marked, the fonts and other dependencies keep their own licenses.