Why it matters
Sequence diagrams are the clearest way to show an API flow or an authentication handshake, but drawing tools make them slow to edit, and text-based tools need a renderer that isn't always available where the diagram ends up: a PDF, a slide or a wiki without Mermaid support.
This builder takes the Mermaid sequence diagram syntax many developers already know and draws a self-contained SVG with everything styled inline, so it renders the same in any browser, document or image viewer. The same diagram comes out as Mermaid for Markdown and as PlantUML for teams that use it, and syntax errors are reported by line.
How to use it
- Write participants, then one message per line.
- Add blocks such as alt or loop, closed with end.
- Check the diagram and any syntax notes.
- Download the SVG, or copy the Mermaid or PlantUML.
FAQ
Is the syntax the same as Mermaid?
It's the sequenceDiagram subset most diagrams use: participants, actors, arrows, activations, notes, blocks, autonumber and title. Paste the Mermaid export into anything that renders Mermaid.
Why is the SVG better than a screenshot?
It's sharp at any size, small, and the text stays searchable and selectable.
Can I convert Mermaid to PlantUML?
Yes. Paste a Mermaid sequence diagram and copy the PlantUML output.
Is my diagram sent anywhere?
No. It's drawn in your browser.
