mark

Mark is a WYSIWYG Markdown editor for reading and editing the files your AI agents write, while they write them.

 
 
 

Install

Mac App Store

Get Mark on the Mac App Store. Installs and updates through the App Store.

Homebrew (macOS, Apple silicon)

brew install --cask xronocode/mark/mark

Developer ID signed and notarized by Apple. Updates through the in-app updater or brew upgrade --cask mark.

Windows (x64)

Download Mark_<version>_x64-setup.exe from the latest release. The installer is not code-signed yet, so SmartScreen shows "Windows protected your PC": choose More info, then Run anyway.

The App Store build and the Homebrew/download build are the same editor with a few differences. See Two editions, same editor.

What's new in 2.5.3

• Picks up where you left off. Launch Mark and the folder and tabs you had open come back, with the same tab active — like Obsidian. Files that are gone are skipped; opening a file from Finder starts with that file. Turn it off in Settings › General › Startup.
• Wide tables at full width. A table wider than the text column opens at its natural width: centred when it fits the window, otherwise starting just inside the edge, with the editor scrolling sideways. «Fit to page» in the table toolbar keeps it in the column, and Mark remembers that per table.
• Column widths that stay. Drag a column border once and the width is kept for that file across restarts — in your Mark profile, never in the Markdown. A double click on the border resets it.
• Updates come to you. The download and Homebrew build checks for a new version once a day and offers Update, Later or Skip this version.
• And the rest. A broom clears Recent in the sidebar; ⌘W closes Settings; the update check in Settings reports in its own row.

The 2.5.0 highlights — diagrams as pictures, a look for each diagram, direct print and PDF — are in CHANGELOG.md.

Why Mark

Agents write plans, specs and reports as Markdown. In a terminal the tables collapse and the diagrams are code. Mark shows the finished page and lets you edit it in place.

Watch your agent write. Keep the file open while an agent works on it. Every save on disk reloads the tab in place and keeps your scroll position, so you can follow a long pass and step in when it finishes. ⌘D shows exactly what the agent changed, against a snapshot Mark takes before every reload.

Start on your notes. The home screen lists recent files and folders, keeps the Guide at hand, and connects your agent with one click.

Write in the finished page. Headings, tables, task lists, footnotes, callouts and front matter look done while you type. When you need the raw Markdown, Split View puts it beside the page.

Diagrams and math inline. Mermaid diagrams, charts, KaTeX formulas and highlighted code render in the document — not in a preview pane — in the colours of the theme. Every diagram type is in the gallery.

Open anything full screen. Any diagram or wide table opens in a clean viewer with zoom, pan and a sticky header for tables.

Copy it clean. Copy as Markdown, as HTML for email, as plain text, or as structured text that keeps paragraphs, bullets, links and tables readable wherever you paste.

Light and dark, one app. Themes come in families — Paper, Ink, Docs, macOS and more — each with a light and a dark member, one title-bar button apart.

Also: a folder sidebar that shows Markdown files only, find in file and in folder, print and PDF export, and no account, analytics or telemetry.

Numbers

Measured on 2026-10-15 on one Apple silicon Mac, Mark 2.3.0. Your numbers will differ.

Mark uses the system WebView (WebKit on macOS, WebView2 on Windows) instead of shipping its own browser engine.

Two editions, same editor

Mark ships in two editions built from the same code. The editor, rendering, theme families, live reload, Split View, copy formats, print and PDF export, Share, and the ⌘D diff against Mark's own snapshots are the same in both.

Why the difference? The App Store sandbox does not let an app run other programs (git, pandoc, screencapture) or open a local server, so those features are left out of the App Store build.

Set up your agent

Add this to your agent's instructions (CLAUDE.md, AGENTS.md, a system prompt, or whatever your agent reads):

When you produce a plan, spec, report, or any document longer than ~50 lines,
write it to a .md file and open it for the user:

    open -a Mark <file>.md        # macOS

The user reads and edits it in Mark, which reloads the file whenever it changes
on disk. When the file changes after you wrote it, read it again: the user left
corrections or comments inline. Treat those edits as your next instruction.

Your agent writes, Mark renders, you edit, the agent reads your changes.

You: "Write an implementation plan for the new auth module."

The agent writes plan.md and runs `open -a Mark plan.md`.

You read it with the tables and Mermaid diagrams rendered.
You delete step 3, rewrite step 5 and add a note: "use JWT, not sessions".
Save.

The agent reads the file again:
"Step 3 removed, step 5 now uses JWT. Proceeding with the revised plan."

Add to your agent's instructions:

    Maintain a knowledge base in docs/kb.md.
    After each significant decision, append a dated entry.
    The user may reorganise or annotate entries in Mark;
    treat their edits as authoritative.

Open docs/kb.md in Mark once and leave it open.
Every time the agent appends, the tab reloads.

The Mark binary accepts these flags. On macOS, open -a Mark --args --watch notes.md passes them when Mark starts.

Diff view (⌘D) compares the file with Mark's own snapshot from the last reload — no set-up needed. Without a snapshot it falls back to a notes.md.before file next to the document, or to the last git commit in the Homebrew build. Want an explicit baseline? Have your agent copy the file to .before before it edits, and you see exactly what changed.

Build from source

Requirements: Node.js 22, stable Rust, and on macOS the Xcode command line tools.

git clone https://github.com/xronocode/mark.git && cd mark
npm ci
npm run tauri dev       # development build with hot reload
npm run tauri build     # release bundle in target/release/bundle

See CONTRIBUTING.md for tests and pull requests.

Acknowledgements

Mark began as a port of MarkText and would not exist without it:

• @Jocs created MarkText: the muya WYSIWYG engine, the theme system, and the inline editing model Mark still builds on.
• @Tkaixiang maintained the community fork that kept MarkText alive with security fixes (CVE-2023-2318), crash fixes and the Mermaid v11 upgrade. Mark's early Electron phase was based on that fork.
• The MarkText community: years of issues and pull requests about what a good Markdown editor should do.
• The Tauri team, for a framework that runs on the system WebView.

Contributing

Bug reports, ideas and pull requests are welcome. Start with CONTRIBUTING.md. To report a security problem, see SECURITY.md.

Documentation: mark.xronocode.com. If Mark is useful to you, you can support it on Ko-fi.

License

MIT. Maintained by @xronocode.