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Mermaid Live Editor

Edit Mermaid syntax with a live diagram preview and export to SVG or PNG.

SIMILAR DEVELOPER

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Base64 Encoder/Decoder

Fast conversion between string and base64 encodings

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JSON Tree Viewer

Inspect nested JSON structures and fix syntax errors

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JWT Encoder/Decoder

Decode a JWT to read its header, payload and expiry status. Decoding only: signatures are not verified.

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WHAT IS MERMAID LIVE EDITOR?

Edit Mermaid syntax and preview flowcharts, sequence, class and ER diagrams, Gantt charts, mindmaps and more. Built-in templates and themes, pan and zoom, and SVG/PNG export.

How to use?

  1. Start from a template or type Mermaid syntax.
  2. Preview on the right; switch theme, zoom or pan as needed.
  3. Export as SVG or PNG.

Frequently asked questions

Does the diagram content get sent to a server?

No. All editing and rendering happens entirely in your browser — this tool has no corresponding API route, so your diagram source never leaves your device.

Why is the security level "strict" instead of "loose"?

This tool always sets Mermaid's securityLevel to strict, never loose — that prevents arbitrary scripts or click handlers embedded in diagram syntax from executing, so pasting someone else's diagram source stays safe.

Does the preview go blank if I make a syntax mistake?

No. When a syntax error is detected, this tool shows the error message under the source editor while the preview keeps showing your last successfully rendered diagram instead of clearing it.

Templates:
Source
Preview
Rendering…