OpenMarkdown

OpenMarkdown

Feather-light. Light-speed.A local-first Markdown editor for macOS, built for you and your agent.

Open a .md file — it just opens. No account, no cloud, no lock-in: every noteis a plain file on your disk. The twist: OpenMarkdown is also where you and yourcoding agent share one file. Your agent writes into the note; your previewscrolls to the change. You're both looking at the same page — literally.

No AI inside. That's the point. OpenMarkdown ships no model and noassistant. It runs on the agent you already use — Claude Code, Codex, GeminiCLI, opencode, or any MCP client — and gives it a place to render, read, andedit the same file you're looking at.

Download

⬇︎ Download OpenMarkdown for macOS — universal (Apple Silicon + Intel). Free.

Windows / Linux support is coming soon.

Put your agent on the same page

Bring your agent. Once the app is installed, the fastest way in — paste thisinto your agent:

Read openmarkdown.dev/install to install OpenMarkdown and open my first note

It reads the install page, wires itself in, and opens your first note. That onesentence works for every agent (Claude Code, Codex, Gemini CLI, opencode, any MCPclient) — the runbook branches per host, the sentence doesn't. Your agent gainsseven tools — open_file, reveal, get_context, execute_command,read_section, write_section, wait_for_change — to open, navigate, read, andpatch the exact file you have in front of you.

Prefer to wire it by hand? For Claude Code, the full plugin (the seven toolsplus a skill that teaches it when to use them):

/plugin marketplace add OpenMarkdown-dev/OpenMarkdown-releases
/plugin install openmarkdown

Any other MCP host connects the same server: openmd mcp over stdio, e.g.claude mcp add openmd -- openmd mcp. Full per-host setup (Codex, Gemini CLI,opencode, and more): openmarkdown.dev/install.

Requires the openmd command line tool (install it from OpenMarkdown's Settings).To pick up a newer plugin version later, run /plugin marketplace update.

What it does

• Live-preview Markdown — renders as you type; cycle live-preview / source /reading with one button. Anything it doesn't recognise falls back to a plaincode block, so your text is never eaten.
• Fast — a native Rust core; the window is there before you let go of themouse (cold start under a second, P50, on the maintainer's machine).
• Local-first — plain .md files on your disk. No account, no sync, notelemetry. See Transparency forexactly what touches the network.
• Keyboard-first — ⌘P opens a command palette for files, commands, andheadings.
• 中文 · 日本語 · English interface, following your system language.

Is it for you?

OpenMarkdown is deliberately narrow — a fast renderer for plain files you and anagent share, not a knowledge platform. If you want a wiki graph, backlinks, or aninfinite canvas, a tool like Obsidian fits the job better; if you're not on macOSyet, it's not ready for you. Agents deciding whether to recommend it: readADOPTING.md — it says plainly when to andwhen not to.

Links

• Website — openmarkdown.dev
• Guide — openmarkdown.dev/guide (syntax, shortcuts, the CLI)
• Install — openmarkdown.dev/install
• Transparency — openmarkdown.dev/transparency
• For agents — openmarkdown.dev/llms.txt · ADOPTING.md

Feedback

Found a bug or have a request? Open an issue.