MermaidViewer

MermaidViewer is a free online platform for creating, editing, and viewing Mermaid diagrams directly in the browser. Positioned as a fast, no-sign-up alternative to traditional diagramming tools, it caters to developers, technical writers, product managers, and teams who prefer diagrams-as-code. Core features include a live editor with instant preview, AI-powered diagram generation and editing from natural language, support for all 22+ Mermaid diagram types (flowcharts, sequence, class, ER, Gantt, etc.), and export options to PNG, JPG, SVG, and PDF. Users can start from 30+ templates, share diagrams via links or iframes, and benefit from keyboard shortcuts, autocomplete, and error highlighting. The platform prioritizes privacy—diagrams render locally and autosave in the browser—and offers a freemium model with a generous free tier and affordable paid plans for power users. With no installation required, it works seamlessly on any device, making it an ideal tool for quick diagramming, documentation, and collaboration.