Diagram & Sequence Workbench

Client-side architecture canvas (Excalidraw) and Mermaid diagram editor for sequences, flows, and charts — PNG/SVG/JSON export, local auto-save.

Privacy: 100% Client-Side. Your data never leaves this browser tab. Processing uses Web APIs and client-side libraries only.

Draw architecture boards or author Mermaid diagrams (sequence, flowchart, and more) entirely in your browser — no uploads, iframes, or third-party diagram hosts.

Excalidraw docsGitHub

Auto-saves the scene to this browser. Fonts are self-hosted; nothing is uploaded.

Why a client-side diagram workbench?

Teams sketch systems, APIs, auth flows, and ops runbooks constantly. Hosted whiteboards and diagram SaaS can leak proprietary architecture.

This workbench embeds Excalidraw and Mermaid locally with self-hosted fonts, starter templates, a personal shape library, and PNG/SVG/JSON export — nothing leaves the tab.

How to use this tool

  1. Open Visual Canvas to draw boxes, connectors, and labels; use the library panel to save/reuse shapes; export PNG/SVG or save/load the Excalidraw JSON scene (auto-saved locally).
  2. Switch to Sequence Code, pick a Mermaid template or paste your own (sequence, flowchart, etc.), then export the rendered SVG/PNG.
  3. Use dark/light theme — both engines follow the site theme.

Frequently asked questions

Does Excalidraw call a CDN?

No. Fonts are copied into this app on install and served from /excalidraw/fonts. Rendering stays in the browser.

Are diagrams uploaded?

No. Scenes, Mermaid source, and your personal shape library persist only in this browser's localStorage unless you download an export.

Can I use the Excalidraw library?

Yes. Open the library panel in the canvas to add selected shapes to a personal library stored locally. Remote library installs from the public Excalidraw catalog are disabled to keep the tool offline.