I've used this in the past for collaborative diagramming sessions and love its ease and simplicity, but the point of Mermaid is its portability - ie. can be embedded in Markdown docs and viewed in various editors/platforms.

Thanks @maho! We're hoping to keep the improvements flowing. I'm non-technical but from my perspective I thought Mermaid sequence diagram functionality really shines! Would love to fill the gap in my knowledge. What is better about https://sequencediagram.org/ than Mermaid sequence diagrams?

Agreed. I’ve tried other editors but so far I’ve always come back to sequencediagram.org — it just works, low fuss.

FWIW, I find MermaidChart's sequence diagram editor better than the sequencediagram.org one!

sequencediagram.org is using PlantUML I believe, so you can do these locally without their website.