This mermaid live editor turns plain Mermaid code into rendered diagrams as you type, with rendering that starts the moment you paste. Drop in a flowchart, sequence diagram, gantt chart, class diagram, or state diagram and watch the SVG appear instantly beside your source. It is built for developers, technical writers, and architects who keep diagrams in docs, README files, or design notes and want a quick way to preview and export them. The mermaid diagram renderer auto-detects light and dark themes to match your view, reports syntax errors inline so you can fix them fast, and lets you download the result as a clean SVG. Because everything is processed locally in your browser, your diagram source never leaves your device and nothing is uploaded to a server.
Features
Live rendering of Mermaid code to SVG as you type
Supports flowcharts, sequence, gantt, class, state and more diagram types
Inline syntax error messages pinpoint problems in your code
Auto-detects light and dark theme to match your current view
Download the rendered diagram as a clean SVG file
Strict security mode sanitizes diagram content during rendering
Runs entirely in your browser so nothing is uploaded to a server
How to use the Mermaid Diagram Renderer
Paste or type your Mermaid code into the input box.
Watch the diagram render automatically in the output panel.
Fix any inline syntax error messages if they appear.
Switch your browser or app theme to preview light or dark styling.
Click download to save the result as diagram.svg.
Example
Input
graph TD
A[Start] --> B{Works?}
B -->|Yes| C[Ship it]
B -->|No| D[Fix it]
D --> B
Output
A rendered SVG flowchart: a Start box flows into a Works? decision diamond, the Yes branch points to Ship it, the No branch points to Fix it, and Fix it loops back to the decision.
A simple flowchart rendered to downloadable SVG.
Common errors & troubleshooting
Parse error or "Syntax error in text" shown instead of a diagram. — Check the first line declares a valid diagram type (e.g. graph TD, sequenceDiagram, gantt) and that arrows and brackets are balanced.
Node labels with special characters like parentheses or quotes break rendering. — Wrap the label text in double quotes, for example A["My (label)"], so Mermaid treats the characters literally.
Diagram renders but colors look wrong against your background. — The renderer follows your light or dark theme automatically; switch your app theme to get the matching styling.
Indentation or tabs cause unexpected layout in flowcharts. — Use consistent spaces for indentation and keep each node or link on its own line.
Frequently asked questions
What is the Mermaid live editor?
It is an in-browser tool that converts Mermaid code into a rendered diagram in real time, so you can preview flowcharts, sequence diagrams, and more beside your source and export them as SVG.
What diagram types does the Mermaid live editor support?
It renders standard Mermaid syntax including flowcharts, sequence diagrams, gantt charts, class diagrams, and state diagrams, the same syntax used in GitHub and many docs tools.
How do I export a Mermaid diagram as an image?
Once your diagram renders, click download to save it as an SVG file you can drop into docs or open in any vector editor.
Why does my Mermaid diagram show a syntax error?
The renderer validates Mermaid code and shows the parser message inline; most errors come from a missing diagram-type declaration or unbalanced brackets and arrows.
Does the rendered diagram match my dark mode?
Yes. The Mermaid live editor detects whether you are viewing in light or dark mode and applies the matching Mermaid theme automatically.
Is my Mermaid diagram code kept private?
Yes. Your Mermaid source is rendered locally in your browser and never leaves your device, so nothing is uploaded to a server.
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