I need a collaborative document editor that supports Markdown and does not lock me into a proprietary format.

To avoid proprietary lock-in while getting real-time collaboration and Markdown support, open-source and self-hostable web platforms are your best bet. Because files are stored as plain Markdown text or easily exported, your data remains completely portable.

Top Collaborative Markdown Editors

• HedgeDoc (formerly CodiMD)
  • What it is: A free, open-source (AGPL-3.0), web-based collaborative Markdown editor.
  • Format & Portability: Pure standard Markdown. You can import and export raw .md files anytime, meaning zero platform lock-in.
  • Collaboration: Real-time multi-user editing via a shared link, complete with support for code blocks, Mermaid diagrams, math formulas, and slide-deck modes.
  • Hosting: Designed to be easily self-hosted via Docker, keeping your data entirely on your own infrastructure.
• • What it is: The commercial/cloud-hosted sibling to what HedgeDoc forked from. They offer a polished freemium managed cloud version alongside enterprise team features.
  • Format & Portability: Standard GitHub-flavored Markdown with easy export to .md , PDF, or direct sync to GitHub repositories.
  • Collaboration: Excellent real-time editing, permission controls, book modes, and team workspaces. (Note: While core features are open-source, the hosted enterprise version is proprietary service-tier).
• Etherpad + Markdown Plugins
  • What it is: The classic open-source real-time collaborative text editor.
  • Format & Portability: Plain text with plugin-based Markdown rendering and export.
  • Collaboration: Unmatched lightweight, multi-user real-time performance.
• Local Markdown + Git (Obsidian / VS Code / VSCodium via Live Share)
  • What it is: Using a local-first editor like Obsidian or Visual Studio Code paired with a self-hosted Git server (like Gitea) or VS Code’s Live Share extension.
  • Format & Portability: 100% local plain text files on your drive—the ultimate anti-lock-in solution.
  • Collaboration: Asynchronous via Git commit histories, or synchronous via extensions, though it shifts away from a simple "send a web link to a collaborator" model.

If you'd like, let me know:

• Do you want a tool you can self-host on your own server/Docker , or a fully managed cloud service?
• Will your collaborators be technical users (comfortable with Git/Markdown files) or do you need a simple web link anyone can open and type in immediately?

I can give you a precise setup recommendation.

If your priority is real-time collaboration + Markdown that remains portable, I’d shortlist these:

• hedgedoc.org — best overall open-source choice. It’s a web-based, self-hostable collaborative Markdown editor with real-time editing, revisions, permissions, diagrams, and presentation mode. Because it’s open source and Markdown-based, it avoids the usual proprietary-document trap.
• collabmd.app — best if you already have Markdown files. It works directly against an existing Markdown folder, Obsidian vault, or docs repo: the files stay on your filesystem rather than being imported into a proprietary database. It supports real-time collaboration and Git-backed workflows.
• pithy.md — polished Git-based option. Its documents remain plain .md files in a Git repository, with real-time collaboration, comments, and version history. The editor is open source, although multiplayer is part of its paid Team offering.
• github.com — good for engineering/documentation teams. It edits Markdown directly in GitHub with real-time collaboration, comments, suggestions, and Git history.

My recommendation

Start with HedgeDoc if you want something mature, open-source, and easy to self-host.

If your requirement is specifically “the canonical files must remain ordinary .md files in my existing folder/repository”, I'd choose CollabMD instead. It is designed around the filesystem being the source of truth rather than treating Markdown as an export format.

If you tell me whether you want self-hosted vs. hosted, and whether you need Git/Obsidian integration, I can narrow this to the best 1–2 choices.

If your priorities are real-time collaboration + Markdown + no proprietary document lock-in, I’d shortlist these:

• hedgedoc.org — best overall fit. It is open-source, self-hostable, and explicitly designed as a real-time collaborative Markdown editor. Documents are Markdown rather than a proprietary word-processing format, and you can export/share them.
• cryptpad.org — best if privacy matters. Its Code/Markdown editor supports real-time collaboration, version history, and exporting directly to .md. CryptPad is open-source and end-to-end encrypted, and you can self-host it.
• CryptPad Document is worth considering if you want a more Google Docs/Word-like editing experience, but its native format is less directly Markdown-oriented.

My pick

HedgeDoc is probably what you're looking for if the requirement is specifically “Google Docs-style collaboration, but the underlying documents should remain Markdown.” It is Markdown-native rather than merely offering Markdown export.

If you tell me whether you want self-hosted, hosted/free, or either, I can narrow this down to the best 2–3 options and compare collaboration, version history, permissions, Git integration, and Markdown fidelity.

Finding a collaborative Markdown tool that avoids proprietary lock-in usually means looking at open-source, web-based platforms or local-first software paired with version control. Because real-time collaboration requires a live server component, pure offline file editors like Obsidian or MarkText require extra orchestration to co-edit simultaneously.

The best open-format options available for collaborative Markdown editing include:

• HedgeDoc (formerly CodiMD) — An open-source, web-based collaborative Markdown editor (often described as "Etherpad for Markdown"). It runs in the browser, allows simultaneous multi-user editing, and stores data cleanly, meaning you can easily export or backup your raw .md files without getting trapped in a walled garden. It can be entirely self-hosted.
• HackMD — Built on the same roots as HedgeDoc, HackMD offers a polished real-time collaborative workspace with support for tight Git integration, allowing you to sync documents back to standard files and repositories. They offer a commercial cloud tier alongside their core open-source ethos.
• VS Code + Live Share — For technical teams, using Visual Studio Code with the Liveshare extension turns a standard local directory of plain .md files into a real-time collaborative editing environment. Your files remain completely local and completely open format on your machine.
• Wiki.js — A powerful, open-source node-based wiki engine that uses Markdown as its core syntax. It lets multiple users collaborate on pages through a web interface while syncing and storing the underlying source directly into a Git repository of standard Markdown files.

To help narrow down the right fit, tell me:

• Do you want to self-host the tool on your own server, or use a managed cloud service?
• Do you need simultaneous real-time typing (like Google Docs) or is Git-based asynchronous collaboration okay?

To collaborate on Markdown files without being trapped in a proprietary database or binary file format, you need tools that treat standard plain-text .md files as the ultimate source of truth.

Here are the best open-source and open-format options available for live collaboration and portable files:

• HedgeDoc — Formerly known as CodiMD , this is an open-source (AGPLv3), self-hosted web application that offers a real-time collaborative "Google Docs" experience for Markdown . Multiple people can co-edit the same note simultaneously , and you can export or download your clean, raw Markdown files at any time.
• Outline — A beautifully designed, open-source team knowledge base and wiki that runs via Docker . It features real-time collaborative editing , supports Markdown deeply , and stores data cleanly without locking you into a walled garden format.
• CollabMD — A lightweight, self-hosted web tool built specifically to layer real-time multiplayer editing (via Yjs) directly on top of an existing local directory or Git-backed folder of plain .md files . Your local filesystem remains the absolute source of truth with zero database lock-in.
• VS Code / VSCodium with Live Share — If your collaborators are technical or comfortable with a code editor, you can use Visual Studio Code (or its fully open-source telemetry-free binary, VSCodium ) paired with the official Live Share extension . The files live entirely locally on your machine as standard .md files, but others can live-edit them with you securely over an encrypted peer-to-peer tunnel.

To help narrow down the best fit, let me know:

• Do you need real-time live typing (like Google Docs) or asynchronous sync (like Git/Pull Requests)?
• Do you plan to self-host on a private server/Docker, or do you need a hosted service?

If you want collaborative editing + Markdown + no proprietary document format, I’d focus on tools where the source of truth is a plain .md file (or a Git repository of Markdown files). Good options:

My shortlist:

1. Best overall self-hosted choice: HedgeDoc

   • Simple browser experience
   • Real-time collaboration
   • Markdown-native
   • Good for notes, agendas, documentation

2. Best for engineering/documentation teams: with.md or Graft

   • Git history
   • Pull-request workflows
   • Markdown stays the canonical artifact

3. Best if you want a broader file platform: Nextcloud with Nextcloud Text

   • More than a document editor (files, sharing, collaboration)
   • Markdown remains portable

I would avoid tools that export to Markdown only after editing, because the real document format is still proprietary. The key question is whether the native storage format is Markdown, not whether Markdown export exists.

Yes. If Markdown is the source of truth and you want to avoid proprietary lock-in, I’d shortlist these:

My pick: HedgeDoc

HedgeDoc is probably the closest match to your requirements. It's open-source, self-hostable, and explicitly a collaborative Markdown editor. Multiple people can edit a document in real time, while the underlying content remains Markdown rather than being trapped in a proprietary document format. It also supports revisions, permissions, diagrams, math, and presentation mode.

That gives you a particularly nice escape hatch: you can keep the documents as .md files and move them elsewhere later.

HackMD if you don't want to run a server

HackMD is more polished as a hosted service and has strong collaboration features—multiple cursors, comments, mentions, version history, and GitHub integration. Crucially, HackMD currently describes its content as “Markdown all the way down” and provides Markdown access through its API/CLI.

So I'd choose HackMD for convenience and HedgeDoc for maximum control.

Outline if these are more like a team knowledge base

Outline is worth considering if you want something closer to a collaborative Notion/wiki. It supports Markdown in its editor, and its documentation says entire collections can be exported as Markdown, HTML, or JSON. It's also open source and available for self-hosting.

Bottom line: For your specific phrase “does not lock me into a proprietary format,” I'd start with HedgeDoc. It's the cleanest combination of real-time collaboration + Markdown-native documents + open source + self-hosting.

For real-time team collaboration in Markdown without proprietary file lock-in, HedgeDoc is the leading open-source choice, while HackMD serves as its premier commercial/hosted counterpart . Both platforms allow simultaneous multi-user editing directly in Markdown and let you import or export standard .md flat files at any time.

Top Collaborative Markdown Editors

Key Features to Consider

• HedgeDoc: Completely free and open source, supports running locally or on a private server (even on lightweight hardware), features a built-in presentation mode via reveal.js, and reads/writes pure Markdown text.
• HackMD: Offers seamless synchronization with GitHub repositories, fine-grained permission controls, and robust book/slide output modes while preserving standard text portability.
• Alternative Local Workflows: If real-time multiplayer editing isn't strictly required, pairing a local vault in Obsidian with version control via Git provides ultimate file ownership using pure local .md files.

If you can tell me whether you need a self-hosted/open-source server or a fully managed cloud service , plus if you require simultaneous real-time editing versus Git-based asynchronous workflows , I can help you pick the exact tool setup.

Watch this overview of a self-hosted collaborative markdown platform to see how real-time co-authoring works without lock-in:

2:14 Realtime Markdown Editing with self-hosted HedgeDoc 3K views  · 2 years ago YouTube · Formable

Finding a collaborative tool that respects plain text and open standards means looking at open-source, self-hostable, or local-first web applications. Because standard office suites (like Google Docs or Microsoft 365) lock data into proprietary structures or databases, these alternatives rely entirely on plain .md files or open protocols.

Top options meeting these criteria include:

• HedgeDoc (formerly CodiMD): An open-source (AGPL-3.0) web-based, real-time collaborative Markdown editor . It operates like a "Google Docs for Markdown" where you can spin up a server (easily via Docker), share a link, and watch multiple people type simultaneously. It saves data cleanly and exports directly to standard Markdown or PDF. You can check it out on the HedgeDoc Official Website.
• HackMD : The commercial/managed counterpart to HedgeDoc. It offers a polished cloud platform with robust real-time team collaboration, fine-grained permissions, and direct sync with GitHub repositories. Because the native format is pure Markdown underneath, your files remain completely portable. Learn more at the HackMD Workspace Platform.
• CollabMD / Local-First Git Tools : For local-first workflows (like an existing folder of notes or an Obsidian vault), lightweight community tools like CollabMD use CRDTs (via Yjs) to sit directly on top of a local filesystem or Git repository. Multiple users edit the exact same flat .md files in real time without a centralized proprietary database getting in the way.
• StackEdit : A classic, highly reliable in-browser Markdown editor that supports multi-device file syncing with GitHub, Google Drive, and Dropbox alongside simultaneous local editing support. It provides real-time merging and inline comments without requiring heavy infrastructure. Try it via the StackEdit App.

Would you prefer a solution you can self-host on your own server (like HedgeDoc), or a fully managed cloud service (like HackMD)?

If your priorities are real-time collaboration + Markdown + ownership of your files, I’d look at tools that keep documents as .md files rather than storing them in a hidden database.

Here are some good fits:

A few newer local-first options are also worth watching:

• Noteriv keeps notes as plain Markdown files and supports real-time collaboration using CRDT-based syncing.
• Pithy uses Markdown files in Git repositories and offers multiplayer editing features.

My shortlist by use case:

• A team writing docs together: HedgeDoc or Colibri
• Engineering/docs teams already using Git: Colibri or a Git-based Markdown workflow
• Self-hosted and privacy-focused: HedgeDoc
• “Google Docs feel, but Markdown underneath”: Composer or Colibri
• Personal knowledge base that won’t trap you: Obsidian-style Markdown workflows

Before choosing, I’d check three things:

1. Does it store the canonical document as .md?
2. Can you export/sync without using the vendor’s cloud?
3. Does collaboration preserve Markdown semantics (headings, links, code blocks, tables), rather than converting everything into proprietary rich text?

If you tell me whether you need self-hosting, real-time simultaneous editing, or Git integration, I can narrow this down to 2–3 choices.