Mermaid Live Editor
About the Mermaid Live Editor
The Mermaid Live Editor lets you write Mermaid diagram code and see the rendered diagram update as you type, then export the result as an SVG. Mermaid is a text-based diagramming syntax where you describe nodes and relationships in plain words and the library draws the picture, which means your diagrams live in version control as readable text rather than as opaque binary image files. The editor closes the feedback loop by rendering your markup instantly, so you can iterate on a flowchart, sequence diagram, or class diagram without leaving the page.
The editor parses your Mermaid source on each change and runs it through the Mermaid renderer to produce vector output, catching syntax errors and surfacing them so you can correct the offending line. Supported diagram types typically include flowcharts, sequence diagrams, class diagrams, state diagrams, entity relationship diagrams, Gantt charts, and pie charts, each with its own concise grammar. Because the output is SVG, the exported diagram scales cleanly to any size and stays crisp in documentation, slides, or printed material.
Common use cases include documenting application architecture, sketching API call sequences, mapping a state machine, planning database relationships, and illustrating a process in a README or wiki. Engineers favor Mermaid because the same diagram can be embedded directly in Markdown on many platforms, and the source diffs cleanly when the design evolves. It works well alongside the XML Tree Viewer for understanding SVG output and complements structured data tools when you want to visualize a schema you just explored.
A practical tip is to start from the simplest valid diagram for your chosen type and add nodes incrementally, watching the live preview so you can immediately see where a connection broke. Keep node identifiers short and give them readable labels in brackets, and when a diagram grows large, use subgraphs or direction declarations to keep the layout legible. Export to SVG once the diagram looks right, since vector output remains sharp at any zoom level.
Frequently asked questions
- What diagram types does Mermaid support?
- Common types include flowcharts, sequence diagrams, class diagrams, state diagrams, entity relationship diagrams, Gantt charts, and pie charts, each defined with its own short text grammar.
- Why export to SVG instead of PNG?
- SVG is a vector format, so it scales to any size without blurring, which keeps diagrams crisp in documentation, slides, and print. A raster format like PNG would pixelate when enlarged.
- Why is my diagram not rendering?
- Usually a syntax error such as a missing arrow, an unclosed bracket, or an invalid diagram-type declaration on the first line. The editor surfaces the problem so you can fix the specific line.
- Can I keep Mermaid diagrams in version control?
- Yes, and that is a key advantage. Because the source is plain text, it diffs cleanly and embeds directly in Markdown on many platforms, unlike binary image files.
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