MermaidStudio — Free & Open-Source Mermaid Diagram Editor
Draw flowcharts, sequence diagrams, class diagrams, Gantt charts and mind maps directly in your browser — with a drag-and-drop visual editor, folders and version history, and an AI assistant that runs locally on your GPU. No account: your diagrams stay on your device.
A free online Mermaid diagram editor — an open-source alternative to the Mermaid Live Editor
Unlike cloud editors, MermaidStudio runs entirely on your machine: the editor works online in any modern browser with zero signup, keeps your diagrams private by default, and adds local version checkpoints you can diff and restore.
- In-browser AI (WebGPU) — generate and fix diagrams with a local LLM; your code never leaves the machine.
- Visual editor — drag-and-drop nodes and edges over the live Mermaid preview.
- Organize — multi-tab workspace with folders, tags and full version history.
- Export & themes — SVG/PNG export with custom styling.
- Private by design — open source (MIT), no accounts, local-first, cookieless analytics, works offline (PWA), English and French.
AI runs locally on your GPU (WebGPU) — your code never leaves your machine.
First use downloads the AI model once (about 400–700 MB). After that it runs entirely offline — nothing is uploaded.
What is MermaidStudio
MermaidStudio is a free, open-source editor for Mermaid diagrams that runs entirely in your browser. You write Mermaid syntax or drag nodes in the visual editor, preview the rendered diagram live, and export SVG or PNG. There is no account, no install — diagrams stay on your device.
How it works
Open the editor and type Mermaid code on the left; the diagram renders on the right as you type. Prefer pointing and dragging? Switch to the visual editor and move nodes and edges directly on the preview. Every save creates a local version checkpoint you can diff and restore — everything persists in your browser's local storage.
Privacy
Your diagrams and settings are stored only on your device — there are no accounts and nothing is uploaded to a server. AI features run locally on your GPU via WebGPU. The site measures usage with Vercel's cookieless analytics and consent-denied Google Analytics 4 (no cookies, no ads; Google processes these pings). Full details on the privacy page.
Free & open source (MIT) · Runs entirely in your browser — even the AI · ★ GitHub · Docs · Changelog · ☕ Ko-Fi · Liberapay · Privacy