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Mermaid Diagram Editor

Type Mermaid syntax to preview flowcharts, sequence diagrams and more in real-time. Download as SVG or PNG.

Last updated: 2026/10/16 Developer Feedback & bug reports
Mermaid Code
Preview

Your diagram will appear here once you enter code.

How to Use

1

Enter Mermaid Syntax

Type Mermaid syntax in the editor on the left. You can also load a template from "Choose a sample" to start instantly.

2

Preview in Real-time

The diagram renders on the right as you type. If there is a syntax error, the details are shown.

3

Save as SVG / PNG

Download the finished diagram as SVG or PNG. Copying the code is also supported.

About the Mermaid Diagram Editor

Mermaid is a diagramming language that lets you describe diagrams with concise, text-based syntax. This tool renders Mermaid syntax in your browser in real-time, instantly visualizing flowcharts, sequence diagrams, Gantt charts and more. Your code is never sent to a server and everything is processed locally, so you can safely create diagrams for internal documents and code reviews.

Features

  • Real-time PreviewDiagrams render as you type, so you can iterate and finish quickly.
  • Many Diagram TypesFlowcharts, sequence diagrams, Gantt charts, class diagrams, ER diagrams and more.
  • SVG / PNG DownloadExport as vector SVG or raster PNG, whichever fits your workflow.
  • Privacy ProtectedAll processing happens in your browser. Your code is never sent to servers.

Use Cases

  • Create flowcharts for system design
  • Draw sequence diagrams for API communication
  • Visualize project schedules with Gantt charts
  • Embed diagrams in READMEs and technical docs
  • Create ER diagrams for database design

FAQ

Is the Mermaid Diagram Editor free to use?
Yes, it is completely free. No registration or installation is required—just open it in your browser.
Is my code sent to a server?
No. Both rendering and image export happen entirely in your browser, so your code and diagrams are never sent to any external server.
Which diagram types are supported?
Flowcharts, sequence diagrams, Gantt charts, class diagrams, state diagrams, pie charts, ER diagrams, mindmaps and other major Mermaid diagram types are supported.
Should I choose SVG or PNG?
SVG scales without quality loss and is easy to edit—great for docs and the web. PNG is easy to paste anywhere, such as chats and slides. Choose based on your use case.
My diagram shows a syntax error. What should I do?
Mermaid is strict about syntax. Check the diagram type declaration at the top (e.g. flowchart TD), the indentation, and arrow symbols. Loading a sample and comparing differences also helps.
Can I use it on my smartphone?
Yes. It works in browsers on smartphones, tablets and PCs.

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Related Guides

Intro to Mermaid: Draw Diagrams from Text — Flowcharts, Sequence Diagrams, and Gantt Learn what Mermaid is from the ground up: how text turns into diagrams, the basic syntax for flowcharts (graph TD), sequence diagrams, and Gantt charts, how to write nodes and arrows, how to use it in GitHub and Notion, and the benefits of managing diagrams as code.