Live Mermaid Diagram & Architecture Studio
Render interactive architecture flowcharts, sequence diagrams, and class diagrams in real time 100% in your browser.
Packages & Libraries: Powered by Mermaid.js (MIT Licensed) client-side diagram rendering engine and W3C SVG DOM exporter APIs.
⚖️ Legal Notice: This diagram rendering studio is provided "as is", without warranty of any kind, express or implied, including but not limited to warranties of merchantability or fitness for a particular purpose. All diagram code rendering and vector exports occur 100% locally inside your browser; zero input text is transmitted to remote servers.
What this tool does
A live Mermaid editor: diagram code on the left, rendered vector SVG on the right, updating on every keystroke. Mermaid is the text-to-diagram language that Git hosting platforms render in READMEs — flowcharts, sequence diagrams, class diagrams, and state machines written as a few lines of readable syntax. Four starter templates cover the main diagram families (themed, like everything around here, around credential architecture), and the Export High-Res SVG button serializes the current render to a file you can drop into docs, slides, or a repository.
How to use it
- Pick a template to get working syntax, or clear the editor and write your own.
- Watch the status line: Live Vector SVG Render (Clean), or a syntax-error flag. Mermaid errors are terse — the offending line is usually the last one you touched.
- Export the SVG before you navigate away.
Where your data goes
Mermaid.js (MIT-licensed) is bundled from npm with this site and lazy-loads on first render — roughly 3.3 MB, kept out of the initial page weight, with no CDN involved, so the editor works offline once loaded. Rendering happens in your browser; nothing you type is saved, synced, or uploaded. There is no autosave and no account — the editor holds your diagram only until the tab closes.
Who it's for
Developers sketching architecture before a design review; anyone writing technical documentation who wants the diagram and its source to be the same artifact; and teams that already use Mermaid in Markdown and want a fast iteration loop with instant feedback instead of a commit-render-refresh cycle. It is also a gentle way to learn the syntax — mutate a template and watch the render react.
Honest limits
- No persistence. Nothing is stored — reload and the diagram is gone unless you exported the SVG or kept the code. A no-account editor cannot silently keep your work, so it doesn't pretend to.
- Strict security level. Mermaid's HTML sanitization is on, so interactive markup embedded in labels is stripped — diagrams render as static SVG by design.
- Errors are flagged, not explained: a malformed line turns the status red, with no line numbers or diagnostics.
- Not a layout editor. No pan or zoom controls, no undo history, no drag-to-rearrange — node placement is Mermaid's automatic layout, tuned through syntax.
Questions people ask
Why does my diagram render on GitHub but not here?
Version drift, usually. Git hosting platforms pin their own Mermaid version, and this site bundles its own — newer syntax occasionally behaves differently between them. Simplify the failing construct, or export from wherever it already renders.
Where does the exported SVG go?
Straight to your downloads folder as a file, assembled locally from the on-screen render. No server round trip, no upload — the export is just your own browser serializing the SVG it is already showing you.
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