MermaidViewer is an online diagram editor that lets you create, preview, and export Mermaid diagrams with live rendering, AI-assisted code generation, and collaboration features — all without installing software.
What is MermaidViewer?
MermaidViewer is a browser-based tool for creating and editing Mermaid diagrams. It takes Mermaid code as input and renders it into a real-time preview of flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, user journeys, Gantt charts, pie charts, requirement diagrams, Git graphs, C4 diagrams, mind maps, and timelines. The platform runs entirely in the browser — no registration required — and is developed by an independent team.
Key Features
- Live Preview — See diagram changes instantly as you type, with no render button needed.
- AI-Assisted Coding — Use a "Generate with GPT-4" button to convert text descriptions into Mermaid code.
- Smart Export — Save diagrams as SVG, PNG, or Markdown with custom DPI settings and support for dark/light themes.
- Enterprise Integration — Deploy privately via Docker with role-based access control.
- Smart Debugging — Syntax error highlighting and auto-correction suggestions to fix code quickly.
- Real-time Collaboration — Share editor links with team members to co-edit diagrams simultaneously.
Who is it for?
- Developers — Create architecture diagrams, flowcharts, and sequence diagrams for documentation or presentations.
- Product managers — Map user journeys, Gantt charts, and requirement diagrams to communicate project plans.
- Teams — Collaborate on technical diagrams in real-time, with version history and sharing controls.
Use cases
- Creating governance committee workflows — Use the pre-built "Governance Committee Decision Flow" template to model agenda intake, voting, and follow-up tracking.
- Planning academic timelines — Use the "Semester Timeline" template to map key academic milestones on a single timeline.
- Designing course lifecycles — Use the "Course Lifecycle" template for needs assessment through delivery and continuous improvement.
- Collaborating on wireframes — Use the "Wireframe Collaboration Flow" template for design brief to engineering handoff.
How does it work?
- Enter Mermaid diagram code in the editor.
- View the diagram rendered in real-time on the same page.
- Export the diagram as SVG, PNG, or PDF, or share the editor link with others.
Pricing
MermaidViewer offers three plans:
- Free — $0, includes 3 diagrams, 5 AI conversations per day, low-res PNG export with watermark, basic sharing, no version history.
- Starter — $69.99/year, 30 diagrams, 500 AI conversations per month, high-res PNG export without watermark, unlimited sharing, 30-day version history.
- Pro — $119.99/year, unlimited diagrams, unlimited AI conversations, all export formats (PNG/JPG/PDF/SVG), advanced sharing with statistics, 100 version history, personal notes and annotations, priority support.
FAQ
Is MermaidViewer free?
Yes, there is a free tier with 3 diagrams and 5 AI conversations per day. Exported PNGs include a watermark on the free plan.
Do I need to install anything?
No, MermaidViewer runs entirely in your browser. No software or plugins required.
What diagram types are supported?
It supports 14 diagram types: flowchart, sequence diagram, class diagram, state diagram, ER diagram, user journey, Gantt chart, pie chart, requirement diagram, Git graph, C4 diagram, mind map, and timeline.
How do I share diagrams with my team?
You can share an editor link that allows real-time co-editing. The Pro plan adds advanced sharing statistics.
How do I export high-quality diagrams?
Export as SVG for vector quality, or as PNG with custom DPI settings. The Pro plan includes all export formats without watermarks.
