Mermaid — The Complete Guide: Diagrams and Schedules Written as Text
Mermaid is an open-source (MIT) library that turns a simple text description into a diagram. Write a few lines — steps, arrows and conditions — and get a flowchart, a Gantt chart or a state diagram. Because the diagram is text, it goes into version control and is as easy to update as any code.
Mermaid
Mermaid open-source project
Diagrams from text — flowcharts, Gantt, sequence and state charts written as code and rendered in Markdown, GitHub and docs.
Get it from the vendorWhat you get
- Many diagram types — flowchart, sequence, class, state and entity-relationship.
- Gantt charts and timelines — for simple project schedules.
- Mind maps — for breaking a topic into subtopics.
- GitHub rendering — diagrams display directly in Markdown files.
- Live editor in the browser — type on one side, see the result on the other.
Who it suits
Mermaid suits documentation of processes, inspection procedures, system structures and schedules that change often — especially when the documentation is already written in Markdown. It is less suitable when you need precise control over styling and the exact placement of every element. The library and the live editor are free for any use; the collaborative platform built around them is a separate commercial product and is not required.
Related tools
For text-based diagrams with a UML focus — PlantUML. For complex graphs with automatic layout — Graphviz. For drag-and-drop editing — diagrams.net.
PlantUML
PlantUML project
Diagrams from text — sequence, state, component and Gantt diagrams written as code and kept under version control.
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Graphviz
Graphviz Project
Draws graphs and network diagrams automatically from a text description.
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diagrams.net (draw.io)
JGraph
A full diagram editor in the browser, with no account required.
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Excalidraw
Excalidraw
A virtual whiteboard with a hand-drawn look — for quick concept sketches, explaining ideas in calls and shared design reviews.
Get it from the vendorThe bottom line
Mermaid is a fast way to add diagrams to technical documentation and keep them current — with no graphic files left behind and forgotten.