What are some of the good, popular, free tools to create UML sequence diagrams? - Quora
Create UML sequence diagrams in draw.io - draw.io
UML Sequence Diagrams - Edraw
SequenceDiagram.org - Free sequence diagram online tool with a clean simple interface and fast client side processing. - SideProjectors | Marketplace to buy and sell & discover side projects.
UML Diagram Tool | Lucidchart
Sequence Diagram Tutorial - Complete Guide with Examples | Sequence diagram, Diagram, Class diagram