MMD Studio is a browser-based Mermaid diagram editor focused on being βFree and open in your browser,β local-first usage, and agent-driven diagram creation. Users can start editing without an account, with source code on the left and a rendered preview on the right. It also offers debounced rendering and syntax error hints. After signing in, users can sync diagrams across devices and share them via stable links.
It supports the main Mermaid diagram types and includes 20+ built-in templates, including flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, Gantt charts, mind maps, Sankey diagrams, Kanban, Architecture, C4, and more. The editor supports syntax highlighting, code folding, search, dark theme, preview zoom, adjustable split panes, and export to .mmd and PNG. Local-first design is a major highlight: when not signed in, diagrams are stored in the browserβs localStorage and can be used offline; after login, they can be synced to the server.
It is fairly developer-friendly. MMD Studio provides a REST API authenticated via Bearer API Token, allowing users to list, read, create/update, delete, and share diagrams. Agent integration is its key differentiator: via mmd.studio/SKILL.md, Claude Code, Claude Desktop, Cursor, or custom tool-calling agents can read the API instructions and create, update, or share diagrams on behalf of users. The documentation includes curl examples, resource fields, error codes, and rate-limit details, making it reasonably complete. However, the available text does not mention an official SDK, nor does it describe an open-source repository or self-hosting option.
The free plan includes unlimited local diagrams, up to 5 synced/shared diagrams, all templates, export, and 10 API requests per day. Pro costs $3/month or $30/year, with unlimited sync/share and unlimited API usage. Lifetime is a one-time $99 purchase. Its strengths are fast onboarding, low pricing, offline usability, and a clear API/Agent workflow. Its limitations are that collaborative editing, invite-based sharing, and version rollback are still marked as soon; the free API quota is low; and the server does not validate Mermaid syntax.
It is suitable for developers, architects, technical writers, small teams, and users of Claude Code/Cursor who need diagrams for documentation, system design, or automated diagram generation. The crawled text does not state how well it works from China. Payments are handled via Stripe, so users in mainland China may need to verify network connectivity and payment availability themselves. Alternatives include Mermaid Live Editor, diagrams.net, PlantUML, Excalidraw, and others.
β This review is compiled from public sources and does not constitute a purchase recommendation. Verify all facts on the vendor's official site. Verify on formtxt.com official site.
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