Maciej Nasinski
January 11, 2025
TL;DR Mermaid allows anyone to define and render professional-quality diagrams quickly. Whether you are a developer documenting a process, a project manager outlining timelines, or a teacher illustrating concepts, Mermaid provides a versatile and efficient solution for all visualization needs. Mermaid is invaluable for illustrating Object-Oriented Programming (OOP) designs and project timelines. Together with LLMs (like ChatGpt), building mermaid diagrams becomes even easier.
Example User Journey Mermaid Diagram:
journey
title Blog Post Visitor Journey
section Visitor Journey
Visitor Arrives: 5
Reads Blog Content: 4
Explores Related Links: 3
Engages with Comments: 4
Shares or Subscribes: 4
Mermaid, a JavaScript-based diagramming and charting tool, is more than just a software. It’s a community-driven project that transforms Markdown-inspired text definitions into dynamic, professional-quality diagrams. Its open-source nature invites everyone to use, contribute to, and enhance it, fostering a vibrant, collaborative community. Since its inception on November 16, 2014 (version 0.1.0), Mermaid has rapidly evolved, with its current version (11.4.1 as of this writing) reflecting ongoing improvements and innovative features driven by its global user base. This continuous evolution ensures that Mermaid remains at the cutting edge of diagramming technology, making it a reliable and forward-looking choice for visualization needs.
Mermaid is supported, or easy to add, in many common tools: GitHub, Quarto, static site generators such as Hugo and Jekyll, and Jupyter Notebooks. It supports flowcharts, Gantt charts, sequence diagrams, UML diagrams and more.
The tool’s text-based nature makes it ideal for version control systems like Git, allowing users to track changes and collaborate effectively. Beginners find Mermaid approachable due to its simple syntax and extensive documentation, while ** advanced users ** appreciate the ability to ** automate and dynamically generate diagrams ** using scripts. Tools like the Mermaid Live Editor and integration with Large Language Models (LLMs) such as ChatGPT further enhance its accessibility, enabling users to describe diagrams in plain text and receive instant, accurate Mermaid code.
Another strength of Mermaid is customization, with options to style diagrams, adjust layouts, and apply themes, ensuring both functionality and visual appeal. Its ability to render diagrams directly in the browser using JavaScript makes it lightweight and easy to integrate into web applications and static sites without relying on heavy dependencies.
Mermaid’s main advantage is that diagrams can live next to the text or code they explain. That makes them easier to review, version and maintain.
For those seeking to experiment with Mermaid diagrams, tools like the Live Editor provide an interactive playground. Here, users can write Mermaid code and see instant previews, making the process of creating and refining diagrams highly efficient. Additionally, platforms like Mermaid AI offer drag-and-drop functionality for creating diagrams visually. This tool caters to users who prefer a more hands-on approach, enabling them to design complex diagrams without delving into code.
Mermaid maintains robust official documentation and a thriving ecosystem. Whether you are just starting out or looking to integrate Mermaid into specialized workflows, these resources will help you get up to speed:
Mermaid’s ecosystem continues to grow at a rapid pace, which means there is likely already an integration available for your favorite platform or workflow.
Mermaid supports a broad variety of diagram types, making it extremely flexible for different use cases:
With such a comprehensive list, it’s easy to tailor Mermaid to your specific project or documentation needs.
Below are a few simpler examples demonstrating different diagram types. Please note we use the echo option for these examples so you see the raw graph code.
gantt
title Project Timeline
section Planning
Task A :done, a1, 2025-01-01, 2025-01-05
Task B :active, a2, 2025-01-06, 2025-01-10
section Execution
Task C : a3, 2025-01-11, 2025-01-20
Task D : a4, 2025-01-21, 2025-01-30
sankey-beta %% source,target,value Electricity grid,Over generation / exports,104.453 Electricity grid,Heating and cooling - homes,113.726 Electricity grid,H2 conversion,27.14
While Mermaid is a powerful and flexible tool for creating diagrams using a text-based approach, there are several alternatives available depending on your use case and preferences:
| Tool | Type | Features | Advantages | Best For | Link |
|---|---|---|---|---|---|
| Mermaid | Text-based | Supports flowcharts, UML diagrams, Gantt charts, and more. | Easy syntax, integrates with GitHub. | Developers, content creators. | Mermaid |
| Graphviz | Text-based | Uses DOT language for graphs and hierarchical diagrams. | Highly customizable. | Graphs and tree structures. | Graphviz |
| PlantUML | Text-based | Rich UML support including sequence and class diagrams. | Great UML support, IDE integrations. | UML modeling. | PlantUML |
| Draw.io | Drag-and-drop | Cloud and local storage, prebuilt templates, supports multiple formats. | User-friendly, no coding required. | Quick flowcharts and wireframes. | Draw.io |
| D3.js | Code-based (JavaScript) | Dynamic, interactive, and data-driven visualizations. | Full control, supports animations. | Custom, interactive visualizations. | D3.js |
| Lucidchart | Drag-and-drop | Collaborative, cloud-based, integrates with productivity tools. | Team collaboration, templates. | Collaborative diagramming. | Lucidchart |
| yEd | Drag-and-drop | Automatic layouts, advanced graph creation tools, offline support. | Free, powerful layout algorithms. | Graphs, network diagrams. | yEd |
| Visio | Drag-and-drop | Extensive templates, enterprise-grade features, integrates with Office 365. | Professional-grade toolset. | Corporate use, professional diagrams. | Visio |
Large Language Models (LLMs), such as ChatGPT, can make Mermaid easier to use by turning a plain-language diagram description into Mermaid syntax. This is useful when you know the structure you want but do not remember the exact syntax.
One of the most powerful features LLMs offer is text-to-diagram conversion, where a simple description of a desired diagram can be instantly translated into the corresponding Mermaid syntax. For instance, providing a prompt like “Create a flowchart where ‘Start’ leads to ‘Decision’, with ‘Yes’ going to ‘Task’ and ‘No’ going to ‘End’” can generate the correct code in seconds. Additionally, LLMs provide instant syntax assistance, helping users navigate the sometimes-tricky process of writing or troubleshooting Mermaid code. They can identify errors, suggest corrections, and optimize diagrams for clarity and functionality.
Beyond assisting with technical details, LLMs also excel at offering creative diagram suggestions. For users unsure of the best way to visualize their data or workflows, LLMs can recommend suitable diagram types, such as flowcharts for processes, Gantt charts for timelines, or sequence diagrams for interactions. This ensures that the resulting visualization aligns perfectly with the intended purpose. Furthermore, customization is made effortless with LLMs, as they can generate code with advanced features like colors, labels, and layouts tailored to specific needs, producing professional-quality diagrams without manual effort.
LLMs are particularly valuable for quick learning, offering examples, explanations, and answers to user queries. Beginners can experiment and refine their understanding of Mermaid through interactive dialogues, while advanced users can streamline workflows by automating repetitive tasks or generating complex diagrams.
Used carefully, LLMs make Mermaid faster to draft. You still need to check the result, especially for larger diagrams where a small syntax mistake can break the whole block.
The vscode-mermAId extension allows users to collaborate with GitHub Copilot to effortlessly generate Mermaid diagrams directly within Visual Studio Code. By interacting with the chat participant, @mermAId, users can request diagram creation tailored to their needs, leveraging Copilot’s advanced AI capabilities. This extension showcases the power of the GitHub Copilot extension APIs, making it an innovative tool for boosting productivity and visualization in development workflows. Key features include the ability to generate diagrams based on the content of the currently open editor. For more information, visit the VScode marektplace.
Mermaid diagrams can be integrated into various platforms.
Here are some quick integration options:
GitHub Markdown: Use fenced code blocks with mermaid to render diagrams directly in your README or other Markdown files. Details can be found in the GitHub Docs.
Jupyter Notebooks: Mermaid is available directly from Notebooks starting from JupyterLab 4.1 and Notebook 7.1. Details
Quarto: Embed diagrams using Mermaid code blocks in .qmd files. Refer to the Quarto Diagrams Documentation.
VS Code: Bunch of Marketplace tools like the Markdown Preview Mermaid Support extension to create and preview diagrams.
Effective diagrams do more than just display information; they help readers quickly grasp complex concepts. Below are some tips to keep your Mermaid diagrams clear, concise, and visually appealing:
Use Consistent Naming
Keep node names and labels meaningful yet short. For example, User vs. User12345 helps maintain clarity.
Simplify Complex Flows
Break large diagrams into smaller, modular sub-diagrams if possible, so that each visual focuses on one concept.
Leverage Mermaid’s Layout Options
Mermaid automatically arranges nodes, but you can guide layout with syntax like graph LR (left-to-right) or graph TD (top-to-bottom) to improve readability.
Use Colors and Styles Sparingly
Mermaid allows styling of elements (e.g., node backgrounds, text, and lines). A consistent color scheme helps readers identify related parts of a diagram without overwhelming them.
Label Edges Wisely
Edge labels should clarify transitions or relationships. Avoid cluttering diagrams with too many text labels; short, descriptive phrases work best.
Whether you’re creating software documentation, educational content, or project planning materials, Mermaid offers a powerful and accessible way to add visualizations. With the ability to integrate into platforms like GitHub, along with interactive tools like the Live Editor and Mermaid AI, Mermaid is poised to remain a cornerstone of modern diagramming and visualization.
Incorporating Mermaid into your workflow not only saves time but also elevates the quality of your content. With its growing ecosystem and widespread adoption, there’s never been a better time to explore the capabilities of Mermaid. From OOP designs to project timelines, Mermaid’s versatility ensures it can meet your unique visualization needs.