mermaid

What is mermaid?

Mermaid is a JavaScript-based diagramming and charting tool that renders Markdown-inspired text definitions to create and dynamically modify diagrams. It is particularly useful for creating flowcharts, sequence diagrams, class diagrams, state diagrams, Gantt charts, and more.

What are mermaid's main functionalities?

Flowcharts

Mermaid allows you to create flowcharts using a simple syntax. The above code creates a flowchart with decision points and different paths.

```mermaid
flowchart TD
    A[Start] --> B{Is it?}
    B -->|Yes| C[OK]
    B -->|No| D[Not OK]
    C --> E[End]
    D --> E[End]
```

Sequence Diagrams

Sequence diagrams can be created to represent interactions between different participants over time. The code sample shows a simple interaction between Alice and Bob.

```mermaid
sequenceDiagram
    participant Alice
    participant Bob
    Alice->>Bob: Hello Bob, how are you?
    Bob-->>Alice: I am good thanks!
```

Gantt Charts

Mermaid supports Gantt charts for project planning and scheduling. The code sample demonstrates how to define tasks and their durations.

```mermaid
gantt
    title A Gantt Diagram
    dateFormat  YYYY-MM-DD
    section Section
    A task           :a1, 2023-01-01, 30d
    Another task     :after a1  , 20d
    section Another
    Task in sec      :2023-01-12  , 12d
    another task     : 24d
```

Class Diagrams

Class diagrams can be used to represent the structure of a system by showing its classes, attributes, and methods. The code sample shows a simple class diagram with inheritance.

```mermaid
classDiagram
    class Animal
    Animal : +String name
    Animal : +int age
    Animal : +void eat()
    Animal : +void sleep()
    class Dog
    Dog : +String breed
    Dog : +void bark()
    Animal <|-- Dog
```

State Diagrams

State diagrams represent the states of an object and transitions between those states. The code sample shows a simple state diagram with different states and transitions.

```mermaid
stateDiagram-v2
    [*] --> Still
    Still --> [*]
    Still --> Moving
    Moving --> Still
    Moving --> Crash
    Crash --> [*]
```

Other packages similar to mermaid

flowchart.js

Flowchart.js is a simple library to create flowcharts using JavaScript. It is less feature-rich compared to Mermaid but is easier to use for basic flowchart needs.

js-sequence-diagrams

js-sequence-diagrams is a library specifically for creating sequence diagrams. It offers a more focused approach to sequence diagrams but lacks the versatility of Mermaid.

chart.js

Chart.js is a popular library for creating various types of charts and graphs. While it does not support diagrams like flowcharts or sequence diagrams, it excels in creating data-driven charts.

d3

D3.js is a powerful library for creating complex and interactive data visualizations. It offers more flexibility and control compared to Mermaid but requires a steeper learning curve.

README

mermaid

Generation of diagrams and flowcharts from text in a similar manner as markdown.

Ever wanted to simplify documentation and avoid heavy tools like Visio when explaining your code?

This is why mermaid was born, a simple markdown-like script language for generating charts from text via javascript.

The code below would render the following image

Code	Rendered diagram
graph TD; A-->B; A-->C; B-->D; C-->D;
sequenceDiagram participant Alice participant Bob Alice->>John: Hello John, how are you? loop Healthcheck John->>John: Fight against hypochondria end Note right of John: Rational thoughts <br/>prevail... John-->>Alice: Great! John->>Bob: How about you? Bob-->>John: Jolly good!

Further reading

• Usage
• Flowchart syntax
• Sequence diagram syntax
• Mermaid client
• Demos

Credits

Many thanks to the d3 and dagre-d3 projects for providing the graphical layout and drawing libraries! Thanks also to the js-sequence-diagram project for usage of the grammar for the sequence diagrams. Thanks to Jessica Peter for inspiration and starting point for gantt rendering.

Mermaid was created by Knut Sveidqvist for easier documentation.

Knut has not done all work by him self, here is the full list of the projects contributors.

Changelog

0.5.4 (2015-10-19)

Full Changelog

Closed issues:

• Weird bug in live editor when using words with substring end #184
• Custom icons #15
• Marker-end arrow cannot be shown for URL with query parameter #225
• Please update bower's D3 version #221
• Set log level from mermaid configuration #220
• Width fixed to 400px #204
• render to png from the cli does not display the marker-end arrow heads #181
• Links in sequence diagrams #159
• comment characters %% cause parse error #141
• Add a reversed asymmetric shape #124
• Add syntax for double headed arrows #123
• Support for font-awesome #49

Merged pull requests:

• Allow end as a substring of vertex id #224 (spect88)
• Remove duplicate npm dependencies: d3 and he #223 (spect88)