Loading page
Feature checklists make every tool look equivalent. This table leads with the three things that actually differ — what it costs you before it works, whether your files leave your device, and where the free version stops.
| SequenceDiagram.orgsequencediagram.org | PlantUML Online Serverplantuml.com | diagrams.netdiagrams.net | Mermaid Live Editormermaid.live | |
|---|---|---|---|---|
| What it does | Purpose-built editor for sequence diagrams, typed rather than dragged | Renders UML from a text description, with the source encoded in the URL | Full diagram editor that works without an account or a saved file | Write a diagram as text and watch it render beside you |
| What it costs you | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. |
| Your files | Runs on your device | Runs on their server | Runs on your device | Runs on your device |
| Where it stops | Sequence diagrams only — it will not draw any other diagram type. | Diagram source is sent to a public server to render, and the default styling looks its age. | No automatic layout — a fifty-box diagram is fifty boxes you positioned yourself. | Layout is decided by the renderer — if it routes an edge badly there is no way to drag it. |
| Best for |
|
|
|
|
| Category | Diagrams & Whiteboards | Diagrams & Whiteboards | Diagrams & Whiteboards | Diagrams & Whiteboards |
| Last checked | 2026-07-29 | 2026-07-29 | 2026-07-29 | 2026-07-29 |
| Open the site | Open | Open | Open | Open |
This comparison is in the address bar — copy the URL to send it to someone.