HedgeDoc (formerly CodiMD) is an open-source, self-hosted platform for real-time collaborative note-taking in Markdown. Operating under the motto “Ideas grow better together,” it enables multiple users to edit the same document simultaneously in a browser, without requiring any installation on the client side. Rebranded from CodiMD in 2020, HedgeDoc is released under the AGPLv3 license and maintained by a community of contributors.
Key Features
- Web-based: No desktop client required; access and edit notes entirely in the browser.
- Self-hosted: Deploy on your own infrastructure to retain full control over your data and user access.
- Real-time collaboration: Multiple authors can edit the same note simultaneously, with changes reflected instantly.
- Presentation mode: Built-in support for reveal.js allows notes to double as slide decks without additional tooling.
- Visual content: Diagrams and graphs (Mermaid, PlantUML, Graphviz, and others) render inline within notes.
- Permission management: Per-note access controls allow owners to set read, write, or guest permissions.
- Version history: Notes maintain a revision history so earlier versions can be reviewed or restored.
- Low resource requirements: Designed to run on modest hardware, including single-board computers like the Raspberry Pi.
Technical Foundation
HedgeDoc 1.x is a monolithic TypeScript application backed by a SQL database (PostgreSQL, MySQL, or SQLite). The frontend uses a combination of CodeMirror for editing and Markdown rendering libraries for the preview pane.
HedgeDoc 2 represents a complete architectural rewrite, split into a strict frontend/backend separation with a Turbo monorepo structure. The new backend exposes a documented REST API; the frontend is decoupled and communicates exclusively through it. HedgeDoc 2 is currently in alpha and available for preview at hedgedoc.dev.
HedgeDoc 2
The HedgeDoc 2 rewrite introduces several improvements over 1.x:
- Strict client/server separation with no server-side rendering of user content
- A new real-time engine that scales better across concurrent users
- Improved extension and plugin architecture
- Full API documentation for third-party integrations
HedgeDoc 1.x remains in maintenance mode (security and critical fixes only) while the community focuses development effort on HedgeDoc 2.
Related Topics
- Markdown: The markup language HedgeDoc is built around
- Obsidian: Local-first PKM using the same Markdown format, oriented toward personal use rather than collaboration
- Wiki: Collaborative web-based systems for organizing content collectively
- Digital Garden: A related philosophy for networked knowledge publishing