Free Communication Diagram Generator
Create UML communication diagrams with our free tool. Object interactions with sequence numbers.
- Object and actor nodes
- Numbered message sequences
- Association links
- Return message notation
- Export as PNG, SVG, or PDF
Frequently Asked Questions
When should I use communication vs sequence diagrams?
Use communication diagrams to emphasize object relationships and structure. Use sequence diagrams to emphasize timing and message order. They show the same information differently.
What do the numbers on messages mean?
Numbers show message sequence (1, 2, 3...). Nested numbers (1.1, 1.2) show messages triggered by a parent message. This replaces the vertical time axis of sequence diagrams.
Can I convert between communication and sequence diagrams?
Yes, they're semantically equivalent. Communication diagrams emphasize structure; sequence diagrams emphasize timing. Many tools can convert between them.