Mermaid Code is a local-first desktop app. Diagrams live as plain .mmd files — AI agents can read, write, and update them directly. No copy-pasting. No browser automation.
Because diagrams are plain files on your filesystem, any AI coding agent can generate or update them as part of its normal workflow.
# Claude Code example
$ claude "Generate a sequence diagram for the
auth flow and save it to docs/auth.mmd"
Built on Mermaid Live Editor, enhanced with desktop-native capabilities via Tauri.
Open any folder. Browse files in a tree or thumbnail grid. Drag and drop .mmd files directly onto the window.
Open multiple diagrams simultaneously. Tabs and active files are restored per folder on next launch.
Changes are saved automatically with a 2-second debounce. Toggle it off when you need manual control.
Full Vim keybindings in the Monaco editor, including yank-to-clipboard and custom :w / :q commands.
Diagram-type-aware suggestions in the editor. Start typing and get context-sensitive completions.
Set theme, layout direction, and font family using a visual form — no JSON editing required.
Architecture diagrams, database schemas, and business flows never leave your machine. No telemetry, no cloud sync.
Native app on both platforms. "Open with" support — double-click any .mmd file to open it directly.
Mermaid Code includes a built-in Model Context Protocol server. AI agents can interact with the running app directly — no filesystem access required.
list_diagrams
Get the opened folder, list of .mmd files, and the active tab.
preview_diagram
Preview Mermaid code in the Draft tab without saving to disk.
$ claude mcp add --transport http \
mermaid-code-mcp \
http://localhost:37079/mcp
Enable the server: open Mermaid Code → menu icon → toggle MCP Server on.
Download the latest release for macOS or Windows, or install via Homebrew.
$ brew tap m8524769/tap $ brew install --cask mermaid-code
Download the latest installer from the GitHub Releases page. Available for macOS (Apple Silicon & Intel) and Windows.
xattr -dr com.apple.quarantine "/Applications/Mermaid Code.app"