Online UML Editor & Viewer

Write UML as text and watch the diagram build itself: class, sequence, use case, activity and state diagrams are rendered locally by the PlantUML engine — your model never leaves your machine.

Open the UML Editor

How it works

1. Start from a UML template (class, sequence, use case …) or paste your own text
2. The diagram updates live as you type, with syntax errors reported by line number
3. Switch diagram types from the syntax guide — no drawing tools required
4. Export as SVG, PNG, JPG or PDF, or embed it in a Markdown document

Frequently asked questions

Which UML diagram types can I draw?

Class, sequence, use case, activity, state and component diagrams — the same text-based syntax covers all of them.

Do I need to learn PlantUML first?

Not really. Templates and a built-in syntax guide cover the common cases, and plain text like "User -> System : request" already produces a sequence diagram.

Is this free, and does it work without an account?

Yes — no account and no installation. The UML engine runs inside the browser tab, so it also keeps working offline after the first visit.

Can I use the diagrams in documentation?

Export them as SVG for sharp scaling or PNG / JPG for slides, and paste PlantUML blocks straight into Markdown files to render the diagrams inline.