markupmarkdown

Google Docs for Markdown. Comment on, edit, and ship .md files like real documents. Threaded margin comments, a native CodeMirror editor with formatting toolbar and find & replace, one-click GitHub round-trip (open a PR or commit directly), AI revision via Claude — and an MCP server so AI agents review alongside humans.

The problem

Markdown is where a lot of real product thinking lives now — PRDs, RFCs, design docs, release notes, prompt libraries. But the tools for reviewing and editing it are miserable:

• GitHub PRs force every discussion through a code-review workflow. Fine for production code, painful for a quick "this paragraph is unclear" on a brainstorming doc you haven't even branched yet.
• HackMD / Notion / Dropbox Paper lock your content into their format, pull you out of .md, and require everyone to make an account.
• Pasting into Google Docs drops your formatting and now you have two sources of truth.

You just want to drag-select a sentence and leave a comment. You want to edit the document inline when you have a small fix in mind. And when you're done, you want one button that pushes the result back to the file in your repo. Like Google Docs — on a real Markdown file. And in 2026 you probably also want an agent on your review team — but you don't want to give that agent your whole identity, and you definitely don't want it shipping changes without you signing off.

What it does

markupmarkdown is a small self-contained web app: one Go binary plus a React SPA plus MongoDB. Open any Markdown file by URL (raw or github.com/.../blob/.../*.md) or upload one. Drag-select text in the rendered document to leave a margin comment with threaded replies. Or click Edit to open a native CodeMirror editor — formatting toolbar, find & replace, live preview, ⌘S to save as a new revision. Every change propagates to every other open tab in under a second via Server-Sent Events. Resolve threads when you're done. Hand the resolved threads to Claude for a clean revised version. Push any revision back to GitHub as a pull request or a direct commit. Agents join the same review through an MCP server: they read what humans read, leave threads humans can approve, and (with explicit human sign-off) apply the resolved feedback as a new revision.

Unlike Google Docs, edits happen on the actual markdown. No visual mirror, no second source of truth — the file in your repo stays canonical, and the round-trip back to GitHub is one click.

Features

Use cases

• PRD review and revision — share a .md PRD, have product, eng, and design leave inline comments; make the small wording fixes inline; push the cleaned-up version back as a PR.
• RFC / design doc commentary — same workflow, more rigor. Resolve threads as decisions get made; let Claude integrate the resolved feedback into a v2; commit the result back to the repo.
• Release notes drafting — collaborate on Markdown release notes pulled from your repo, then commit the final version back when it's ready.
• Prompt library / SKILL.md review — review the prompt files agents will actually read, with the humans who own them, while the agents themselves can comment and propose edits.
• README / docs polish — open any GitHub README, drag-select awkward sentences, leave comments or edit inline, push the revision back as a PR.

Tech stack

Self-host

Prerequisites: Go 1.25+, Node 20+, MongoDB Atlas (free tier works), a 32-byte master key.

# Clone
git clone https://github.com/jonradoff/markupmarkdown.git
cd markupmarkdown

# Backend
cd backend
cp .env.example .env       # fill in MONGODB_URI + ENCRYPTION_KEY
go run ./cmd/markupmarkdown

# Frontend (separate terminal)
cd frontend
npm install && npm run dev

Open http://localhost:4720/. Deploy to Fly with fly launch — the included Dockerfile is a two-stage build, final image is ~12 MB.

MCP integration

The streamable HTTP MCP server is exposed at /mcp. The full agent guide — conventions, identity model, rate limits, scope hierarchy — is served live at /SKILL.md (and embedded in the Go binary so the deployed URL is always in sync). Tools:

• list_documents — Docs the calling identity has touched
• get_document — Full markdown content + metadata
• list_comments — Threads on a doc, filterable by open/resolved/all
• add_comment — Anchor a new thread to a verbatim substring of the doc
• reply — Reply to an existing thread
• resolve_comment / reopen_comment — Lifecycle
• edit_document — Save a new manual revision (full content)
• patch_comment_anchor — Move a comment's anchor (or pin it doc-level)
• delete_comment — Remove an agent's own (or token-owner's) thread
• list_revisions — Walk the revision chain of a doc
• merge_document — Run the 3-way merge engine
• push_to_github — Open a PR or commit directly
• revise_with_ai — Run Claude over the doc + selected resolved threads (preview by default, accept: true to save as a child doc)

License

MIT — View on GitHub