Free Mermaid diagram editor

KumiDiagrams: a native Mermaid diagram editor for architects.

Create, preview, organize, and export Mermaid diagrams as local files—without giving up the speed of a native desktop app.

Version 0.4.0 · macOS 15+ · Apple Silicon

Built for diagram as code

The editor that keeps architecture diagrams in your flow.

Projects are folders containing plain-text .mmd Mermaid files and optional project configuration.

Edit source, see the preview update while you type, and surface syntax errors immediately.

Get contextual Mermaid suggestions for flowcharts, sequences, state diagrams, and ER diagrams.

Tune themes, fonts, backgrounds, Mermaid look, and connection curves globally, per project, or per diagram.

Save diagrams as PNG files or copy a rendered image straight to the clipboard.

Use Ollama to draft Mermaid source from a description without sending project context to an external service.

In the app

Click a screenshot to enlarge it.

Install on macOS

KumiDiagrams currently ships for macOS 15+ on Apple Silicon. The app and your diagram files stay on your machine.

1
Download the app
Get the KumiDiagrams DMG for Apple Silicon.
2
Move it to Applications
Open the DMG and drag KumiDiagrams.app into your Applications folder.
3
Open KumiDiagrams
Launch it from Applications. If macOS blocks the app, clear the quarantine attribute first.
```
xattr -c /Applications/KumiDiagrams.app/
```