Mermaid Diagram Editor
Write Mermaid syntax, see the diagram render live, download it as SVG.
Diagram renders here
Put it online in seconds
Pagelet turns any HTML file into a live URL on your own subdomain — free, no account needed. Drag a file on the homepage or paste your code.
About the Mermaid Diagram Editor
The Pagelet Mermaid diagram editor turns plain-text Mermaid syntax into rendered flowcharts, sequence diagrams, class diagrams, gantt charts and more — instantly, right in your browser. It's completely free, needs no signup, and your diagrams never leave your device: rendering happens client-side with the official Mermaid v11 library, making it a safe way to visualize AI-generated diagram code from ChatGPT or Claude.
How to use it
- Write or paste Mermaid code in the editor on the left — a flowchart example is pre-filled.
- Press Render and the diagram appears on the right, with syntax errors reported inline.
- Iterate until it looks right; every render is instant.
- Download the result as a crisp, scalable SVG ready for docs, READMEs or slides.
Frequently asked questions
Is the Mermaid editor really free?
Yes — unlimited diagrams, no account, no watermarks. Pair it with Pagelet hosting to publish a page that embeds your diagram.
Which diagram types are supported?
Everything Mermaid 11 supports: flowcharts, sequence diagrams, class diagrams, state diagrams, entity-relationship diagrams, gantt charts, pie charts, mindmaps and more.
Do you store my diagrams?
No. Rendering happens in your browser and nothing is uploaded. If you want to keep a diagram, download it as SVG.
Part of the free pagelet tool set — no account needed. Want to publish a page too? Drag a file and it's live.