About SimpleMermaid

SimpleMermaid was born out of a simple frustration: creating and sharing technical diagrams shouldn't require a login, a subscription, or a heavyweight desktop application. As developers ourselves, we found that every time we needed to sketch out an architecture diagram for a pull request or illustrate a sequence flow for a design review, we were fighting the tools instead of communicating our ideas.

Existing online diagram editors forced us to create accounts, save files to their cloud, and navigate cluttered interfaces filled with features we didn't need. Desktop tools like Visio were expensive and platform-locked. Even lightweight alternatives required dragging and dropping shapes one by one, a painfully slow process when you already know exactly what your diagram should look like.

We knew there had to be a better way. Mermaid.js had already solved the hard problem of rendering diagrams from text, but there was no simple, polished editor that let you write Mermaid code, preview it instantly, and share it with a single link. So we built one. SimpleMermaid launched in late 2024 as a zero-friction diagram editor: open the page, write your diagram, share the link. No accounts, no cloud storage, no complexity. Just diagrams.

We believe that clear technical communication is one of the most undervalued skills in software development. A well-crafted diagram can replace pages of documentation, resolve architectural disagreements in minutes, and onboard new team members faster than any README.

Our mission is to make technical diagramming accessible to every developer, regardless of their organization's tool budget or their personal preference for visual vs. text-based workflows. By keeping SimpleMermaid free, browser-based, and account-free, we ensure that a junior developer writing their first architecture diagram has the same tools available as a principal engineer at a Fortune 500 company.

We are committed to keeping the core editor free and open for the developer community. Great tools shouldn't have paywalls standing between developers and clear communication.

SimpleMermaid is a developer productivity tool designed specifically for software engineers, system architects, DevOps teams, and technical professionals who need to create and share technical diagrams quickly.

Our platform provides a distraction-free environment for creating software architecture diagrams, technical documentation, and system design visualizations using the powerful Mermaid.js syntax that developers already know and love.

• Software Architecture: Design and document system architectures, microservices, and APIs
• DevOps & CI/CD: Visualize deployment pipelines, infrastructure diagrams, and workflows
• Security Engineering: Create threat models, security architecture diagrams, and access control flows
• Technical Documentation: Generate diagrams for wikis, README files, and technical specifications
• Database Design: Build ERD diagrams and data flow visualizations
• Project Management: Create Gantt charts, user journey maps, and process flows

• Full Mermaid.js v10 support with all diagram types
• Real-time rendering with syntax validation
• URL-based sharing with LZ compression
• Export to PNG, SVG, and PDF formats
• Dark mode for extended coding sessions
• Responsive design for mobile and tablet
• No backend dependencies - runs entirely in browser
• Privacy-focused: diagrams never leave your browser

SimpleMermaid is a client-side application that processes everything in your browser. No diagram data is transmitted to any server, making it suitable for use with sensitive architecture and infrastructure documentation.

Key characteristics:

• Zero server-side data processing — diagrams never leave your browser
• No user accounts or authentication required
• No cookies beyond your theme preference
• Compatible with corporate network environments

We don't believe in pretending competitors don't exist. Here's how SimpleMermaid compares to other popular diagramming tools, and when you might choose one over another:

vs. Draw.io (diagrams.net)

Draw.io is an excellent general-purpose visual diagramming tool. It shines when you need pixel-perfect layouts, complex custom shapes, or non-technical diagrams. Choose Draw.io when your diagram needs freeform visual positioning. Choose SimpleMermaid when you want speed: if you can describe your diagram in text, you can create it in seconds rather than minutes of drag-and-drop.

vs. Lucidchart

Lucidchart is a polished enterprise tool with collaboration features, templates, and integrations. It excels at team-wide standardization and real-time collaborative editing. However, it requires an account, stores your data on their servers, and the free tier has limitations. SimpleMermaid trades collaboration features for simplicity and privacy: your diagrams never leave your browser.

vs. PlantUML

PlantUML is the closest alternative in philosophy, also using text-based syntax. PlantUML supports more diagram types and has deeper UML compliance, but requires a server-side renderer (Java-based). SimpleMermaid runs entirely in the browser with zero server dependencies, and Mermaid's syntax is generally considered more readable for newcomers.

The bottom line: SimpleMermaid is purpose-built for developers who want to create and share diagrams with zero friction. If you need advanced collaboration, choose Lucidchart. If you need pixel-perfect layouts, choose Draw.io. If you want the fastest path from idea to shared diagram, SimpleMermaid is your tool.

No Backend, By Design

SimpleMermaid runs entirely in your browser. There is no server processing your diagrams, no database storing your data, and no API calls when you type. This isn't a limitation; it's a deliberate architectural choice. A backend-free design means the tool works offline, loads instantly, and guarantees your diagram content never touches our infrastructure.

URL-Based Sharing

When you share a diagram, the entire diagram content is compressed using LZ-String and encoded into the URL hash. The recipient's browser decompresses it locally. This means shared links are self-contained, work indefinitely (no expiring links), and don't depend on our servers being online. It's a link that contains everything needed to render the diagram.

No Build Step, No Framework

SimpleMermaid is built with vanilla HTML, CSS, and JavaScript. No React, no Vue, no webpack. This keeps the tool fast, auditable, and simple to understand. When you view the source, you see exactly what's running. For a tool that developers trust with their architecture diagrams, transparency matters.

SimpleMermaid believes in the open source community. We are built on top of the incredible Mermaid.js project, and we're grateful for the work of every contributor who makes that library possible. While our platform provides a convenient hosted solution, we encourage developers to contribute ideas, submit example diagrams, and provide feedback to make technical diagramming better for everyone.

If SimpleMermaid has saved you time or helped you communicate an idea more clearly, consider buying us a coffee to help keep the servers running and the tool free for the community.

Have feedback, a feature request, or found a bug? We welcome all input from the developer community. Reach out to us and we'll get back to you as soon as possible.

• Email: hello@simplemermaid.com
• Support the project: Buy us a coffee