About Sequence Diagram Generator

Generate sequence diagrams showing interaction flows between components and actors. Part of the DevTools Surf developer suite. Browse more tools in the Diagrams & Workflows collection.

Use Cases

• Document authentication flows (OAuth2, JWT validation) for new engineers joining a team.
• Design API interaction sequences before implementation to catch integration problems early.
• Communicate microservice call chains to stakeholders without requiring code knowledge.
• Generate incident postmortem diagrams showing the sequence of events during an outage.

Tips

• Use activation boxes to show when each participant is actively processing — without them, sequence diagrams become hard to read for async interactions.
• Group related message sequences with alt/opt/loop combined fragments to show branching and iteration rather than drawing multiple separate diagrams.
• Limit participant count to 6–8 — beyond that, the diagram width forces horizontal scrolling and readers lose track of which lifeline is which.

Fun Facts

• Sequence diagrams were standardized as part of UML 1.0 in 1997 by Grady Booch, James Rumbaugh, and Ivar Jacobson at Rational Software — the same authors who defined the UML specification.
• Mermaid.js, which generates sequence diagrams from text syntax, was created by Knut Sveidqvist in 2014 and became one of GitHub's most-requested features — GitHub added native Mermaid rendering to Markdown in 2022.
• Sequence diagrams are one of the most frequently used of the 14 UML diagram types in practice, second only to class diagrams, according to a 2010 survey of 62 UML practitioners published in IEEE Software.

FAQ

What's the difference between a sequence diagram and a flowchart?

Sequence diagrams show message passing between named participants over time, emphasizing who communicates with whom. Flowcharts show logic flow within a single process — they do not model multiple interacting actors.

Can I show async messages in a sequence diagram?

Yes — use an open arrowhead (compared to filled for synchronous) to indicate an async message that does not block the sender. Return messages for async calls are optional.