Diagrams that don't phone home, then dance for the camera

What it does

OpenFlowKit is a browser-based diagramming studio that sits between whiteboard tools and code-only generators. You can paste Mermaid syntax, describe a system in plain English, or sketch directly on a canvas — it auto-assigns icons from 1,600+ tech brand assets and lays everything out with an off-main-thread ELK engine. The unusual hook is cinematic MP4 export: hardware-encoded H.264 walkthroughs generated faster than real-time via WebCodecs, so your infrastructure diagrams can become conference-slide animations without leaving the browser.

The interesting bit

The project treats “local-first” as a hard constraint, not a slogan. Your API keys for AI generation stay in browser storage; requests go direct to providers, with Ollama as a fully offline fallback. There’s also a first-party MCP server, meaning Claude Desktop, Cursor, or Windsurf can drive the canvas programmatically — a rare case of a visual tool exposing itself as an agent endpoint rather than the other way around.

Key highlights

• Bidirectional diagram-as-code: live-synced Mermaid-compatible DSL and visual canvas
• Auto-icon assignment across developer, AWS, Azure, GCP, and CNCF catalogs based on node label semantics
• Self-correcting AI: bad DSL output is fed back to the model with parser errors for single-turn repair
• Anchored auto-layout: pin specific nodes, let the graph rearrange around them
• MCP server for external agent control; no server-side storage or account required

Caveats

• AI generation requires bringing your own API key for every provider except local Ollama
• The “cinematic MP4” export depends on browser WebCodecs support, which varies
• Star count (597) and relative youth suggest some rough edges in edge-case Mermaid parsing

Verdict

Worth a look if you produce architecture diagrams regularly and resent the cloud-tool tax — especially if you already live in Cursor or Claude and want your agent to draw for you. Skip it if you need real-time multiplayer or deep diagram validation beyond the current Mermaid coverage.