A picture to explains what I mean flowcharts combined with sequence charts (and also the Chinese words there)
So there are 4 participants here (on the top) to collaborate in the event to finish a user action. But inside each participant there is a flowchat to show different workflows based on user's status and input.
First, I would like to know is there a chart or a formal name existed for such chart ?
Second, I use macOS so I am looking for a mac app or a web app. Hopefully it is a free one.
--- update ----
I finally reached the author and he told me it was Visio Cross-Functional Flowchart! I definitely won't use Visio, it is too expensive.