For quick sequence diagrams I really like https://swimlanes.io/ https://swimlanes.io/ It's text-based (build on Mermaid if I'm not mistaken) and really easy t

For quick sequence diagrams I really like https://swimlanes.io/ https://swimlanes.io/ It's text-based (build on Mermaid if I'm not mistaken) and really easy to work with for simple interactions. Also because it's purely text-based you can pass around the full context in the URL. This makes it a little awkward to collaborate vs. a true hosted solution, but it also lowers the barrier to entry significantly.