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:trophy: Mermaid was nominated and won the JS Open Source Awards (2019) in the category “The most exciting use of technology”!!!

Thanks to all involved, people committing pull requests, people answering questions and special thanks to Tyler Long who is helping me maintain the project 🙏

About

Mermaid is a Javascript based diagramming and charting tool that uses Markdown-inspired text definitions and a renderer to create and modify complex diagrams. The main purpose of Mermaid is to help documentation catch up with development.

Doc-Rot is a Catch-22 that Mermaid helps to solve.

Diagramming and documentation costs precious developer time and gets outdated quickly. But not having diagrams or docs ruins productivity and hurts organizational learning.
Mermaid addresses this problem by cutting the time, effort and tooling that is required to create modifiable diagrams and charts, for smarter and more reusable content. The text definitions for Mermaid diagrams allows for it to be updated easily, it can also be made part of production scripts (and other pieces of code). So less time needs to be spent on documenting, as a separate and laborious task.

Even non-programmers can create diagrams through the Mermaid Live Editor, visit Mermaid Overview for the video tutorials.

Want to see what can be built with mermaid, or what applications already support it? Read the Integrations and Usages for Mermaid.

For a more detailed introduction to Mermaid and some of it's more basic uses, look to the Beginner's Guide and Usage.

🖖 Keep a steady pulse: mermaid needs more Collaborators, Read More.

Diagrams that mermaid can render:

Flowchart

graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;

Flowchart

Sequence diagram

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!

Sequence diagram

Gantt diagram

gantt
dateFormat  YYYY-MM-DD
title Adding GANTT diagram to mermaid
excludes weekdays 2014-01-10

section A section
Completed task            :done,    des1, 2014-01-06,2014-01-08
Active task               :active,  des2, 2014-01-09, 3d
Future task               :         des3, after des2, 5d
Future task2               :         des4, after des3, 5d

Gantt diagram

Class diagram - :exclamation: experimental

classDiagram
Class01 <|-- AveryLongClass : Cool
Class03 *-- Class04
Class05 o-- Class06
Class07 .. Class08
Class09 --> C2 : Where am i?
Class09 --* C3
Class09 --|> Class07
Class07 : equals()
Class07 : Object[] elementData
Class01 : size()
Class01 : int chimp
Class01 : int gorilla
Class08 <--> C2: Cool label

Class diagram

Git graph - :exclamation: experimental

gitGraph:
options
{
    "nodeSpacing": 150,
    "nodeRadius": 10
}
end
commit
branch newbranch
checkout newbranch
commit
commit
checkout master
commit
commit
merge newbranch

Git graph

Entity Relationship Diagram - :exclamation: experimental

erDiagram
    CUSTOMER ||--o{ ORDER : places
    ORDER ||--|{ LINE-ITEM : contains
    CUSTOMER }|..|{ DELIVERY-ADDRESS : uses

ER diagram

User Journey Diagram

journey
    title My working day
    section Go to work
      Make tea: 5: Me
      Go upstairs: 3: Me
      Do work: 1: Me, Cat
    section Go home
      Go downstairs: 5: Me
      Sit down: 5: Me

Journey diagram

Installation

In depth guides and examples can be found in Getting Started and Usage.

It would also be helpful to learn more about mermaid's Syntax.

CDN

https://unpkg.com/mermaid@<version>/dist/

To select a version:

Replace <version> with the desired version number.

Alternatively, you can also adjust the version number in the page itself.

Latest Version: https://unpkg.com/browse/mermaid@8.6.0/

Incorporating mermaid to a website

To support mermaid on your website, all you have to do is add Mermaid's JavaScript package

1.You will need to install node v10 or 12, which would have npm

2. download yarn using npm.

3. enter the following command:
    yarn add mermaid

4. You can then add mermaid as a dev dependency using this command:
    yarn add --dev mermaid

To deploy mermaid without a bundler, one can insert a script tag with an absolute address and a mermaidAPI call into the HTML like so:

<script src="https://cdn.jsdelivr.net/npm/mermaid/dist/mermaid.min.js"></script>
<script>mermaid.initialize({startOnLoad:true});</script>

Doing so will command the mermaid parser to look for the <div> tags with class="mermaid" in your HTML Document. From these tags mermaid will try to read the diagram/chart definitons and render them as svg charts.

Examples can be found in Getting Started

Sibling projects

Request for Assistance

Things are piling up and I have a hard time keeping up. To remedy this it would be great if we could form a core team of developers to cooperate with the future development of mermaid.

As part of this team you would get write access to the repository and would represent the project when answering questions and issues.

Together we could continue the work with things like:

  • Adding more types of diagrams like mindmaps, ert diagrams, etc.
  • Improving existing diagrams

Don't hesitate to contact me if you want to get involved!

For contributors

Setup

yarn install

Build

yarn build:watch

Lint

yarn lint

We use eslint. We recommend you installing editor plugins so you can get real time lint result.

Test

yarn test

Manual test in browser: open dist/index.html

Release

For those who have the permission to do so:

Update version number in package.json.

npm publish

Command above generates files into the dist folder and publishes them to npmjs.org.

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.

Tyler Long has became a collaborator since April 2017.

Here is the full list of the projects contributors.