Mermaid Diagram Generator & Editor

What is the Mermaid Diagram Generator?

The Mermaid Diagram Generator is an online editor that helps you create, edit, preview, and export Mermaid diagrams from a single workspace. Instead of switching between a code editor, a Mermaid playground, and an export tool, everything happens in one place. As you write Mermaid syntax in the editor, the diagram updates instantly in the preview panel, making it easy to experiment with different layouts and structures.

Many developers use Mermaid diagrams to document project architecture, application flows, deployment processes, and repository documentation. This editor makes it easy to write Mermaid code, preview the result, and export the final diagram when it is ready.

Built for Documentation and Technical Diagrams

Mermaid has become a popular way to create diagrams using plain text. Instead of manually drawing boxes and arrows, you describe the structure with Mermaid syntax and the diagram is generated automatically. This approach is widely used in GitHub repositories, project documentation, technical tutorials, architecture guides, and software planning documents.

The editor supports the same Mermaid syntax used by GitHub and other documentation platforms, making it easy to create diagrams that can be reused across different projects and workflows.

Real-Time Diagram Preview

As you type Mermaid code, the diagram is rendered instantly in the preview panel. This allows you to see changes immediately without manually refreshing the page or regenerating the diagram. The live preview makes it easier to debug syntax issues, adjust layouts, and refine complex diagrams while you work.

You can also zoom in, zoom out, reset the zoom level, and navigate around larger diagrams directly from the preview area, which is especially useful when working with large flowcharts or architecture diagrams.

Understanding a Mermaid Flowchart

The example below creates a simple flowchart that shows how someone might spend Christmas money. Each line defines a node or a connection between nodes.

graph TD
    A[Christmas] -->|Get money| B(Go shopping)
    B --> C{Let me think}
    C -->|One| D[Laptop]
    C -->|Two| E[iPhone]
    C -->|Three| F[Car]

graph TD

The first line tells Mermaid to create a flowchart. TD means "Top Down", so the diagram flows from top to bottom.

• TD → Top to Bottom
• BT → Bottom to Top
• LR → Left to Right
• RL → Right to Left

A[Christmas]

This creates a node with the identifier A and the visible label Christmas.

The text inside square brackets creates a rectangular box.

A[Christmas]

-->

The arrow operator creates a connection between two nodes.

A --> B

This means node A points to node B.

|Get money|

Text placed between vertical bars becomes a label on the connection.

A -->|Get money| B

The arrow will display the text "Get money" between the two nodes.

B(Go shopping)

Parentheses create a rounded node.

B(Go shopping)

Different brackets create different node shapes.

• [Text] → Rectangle
• (Text) → Rounded rectangle
• {Text} → Decision node
• [[Text]] → Subroutine

C{Let me think}

Curly braces create a decision node. These are commonly used when a process can branch into multiple outcomes.

C{Let me think}

In this example, the user decides between a Laptop, iPhone, or Car.

Creating Multiple Paths

A decision node can connect to multiple options.

C -->|One| D[Laptop]
C -->|Two| E[iPhone]
C -->|Three| F[Car]

Each arrow creates a separate path from the decision node and each path has its own label.

Diagram Result

The flow starts at Christmas, moves to Go shopping, reaches a decision point, and then branches into three possible choices: Laptop, iPhone, or Car.

Built-In Diagram Themes

Different projects require different visual styles. The editor includes multiple Mermaid themes that can be applied with a single click, allowing you to preview how the same diagram looks across different designs.

• Default – Mermaid's standard appearance.
• Dark – Optimized for dark interfaces and technical documentation.
• Forest – A cleaner style with green accents.
• Neutral – Minimal styling for professional documents.
• Base – A simple foundation for custom diagram styling.

Switching themes does not modify your Mermaid code. It only changes the visual presentation of the rendered diagram.

Export Diagrams as SVG or PNG

Once your diagram is complete, it can be exported as either SVG or PNG. SVG exports are ideal for documentation, websites, and GitHub README files because they remain sharp at any size. PNG exports are useful when you need a ready-to-use image for presentations, reports, tutorials, or social media content.

Because the diagram is generated directly from Mermaid syntax, exported files remain clean, scalable, and suitable for professional documentation.

Example Templates and Quick Start Options

Getting started with Mermaid can be difficult if you are unfamiliar with the syntax. The built-in examples menu provides ready-made templates that demonstrate common diagram patterns and help you learn Mermaid faster.

Instead of starting with a blank editor, you can load an example, modify it, and adapt it to your own project requirements.

Who Is This Tool For?

The Mermaid Diagram Generator is designed for developers, technical writers, software architects, educators, DevOps engineers, and anyone who needs to create diagrams from text. It is particularly useful for GitHub documentation, project planning, system architecture diagrams, workflow visualization, and technical tutorials where diagrams need to stay synchronized with source-controlled documentation.