websequencediagrams is a great tool for people who want to generate UML sequence diagrams but who can't or don't want to layout their diagrams.
What it does is allow you to type the diagram specification (free typing) using a little markdown notation (I guess they made up) that's easy to learn. Whenever you change the block of text, the diagram changes. See picture.
This diagram was created from this text:
title Authentication Sequence Alice->Bob: Authentication Request note right of Bob: Bob thinks about it Bob->Alice: Authentication Response
I want to create activity diagrams. But I'm getting a little impaired in my ability to use the mouse with precision. Also I know that if you change the structure of an activity diagram, then that can force radical changes to the layout of the diagram. Seems like a waste of time to be struggling with layout when all you wanted to do was just to represent something in UML.
I understand some people have different styles, but I don't care about the style in my case. It's a worthwhile trade-off.
I can either use windows or the web, but I'd prefer a web-based solution because that's portable.
I would be willing to pay for a tool that did this.