Mermaid Diagram Editor
Create flowcharts, sequence diagrams, and more with live preview.
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About Mermaid Diagrams
Mermaid is a JavaScript-based diagramming tool that uses Markdown-inspired text definitions to create diagrams dynamically. Write simple text and get flowcharts, sequence diagrams, Gantt charts, and more.
Flowcharts
Decision trees, process flows, and system diagrams
Sequence Diagrams
API calls, message flows, and interaction patterns
Class & ER Diagrams
Data models, schemas, and entity relationships
Gantt & State
Project timelines, state machines, and pie charts
Learn more at mermaid.js.org
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How to Create Mermaid Diagrams Online
Mermaid lets you write diagrams in a Markdown-like syntax that renders as SVG — flowcharts, sequence diagrams, ER diagrams, Gantt charts, and more. This Mermaid live editor gives you a real-time preview as you type, so you can iterate on diagrams quickly without installing anything.
Mermaid diagrams are increasingly used in documentation (GitHub, GitLab, and Notion all render them natively), architecture decision records, and technical specs. Writing diagrams as code means they live alongside your source, can be reviewed in PRs, and are easy to update. This editor lets you draft and preview before committing.
The editor supports all Mermaid diagram types: graph/flowchart for flow diagrams, sequenceDiagram for API interactions, erDiagram for database schemas, classDiagram for OOP structures, gantt for timelines, and gitgraph for branch visualizations. Everything renders client-side.
Tips
- Start with
graph TD(top-down) orgraph LR(left-right) for simple flowcharts before trying more complex diagram types. - Use subgraphs to group related nodes:
subgraph "API Layer"makes complex architectures readable. - Mermaid renders natively in GitHub Markdown — wrap your diagram in
```mermaidcode blocks in README files. - If your diagram isn't rendering, check for special characters in labels — wrap them in quotes to escape them.