Overview

Document how systems and components interact over time with this sequence diagram template. A standard tool in software engineering and system design, sequence diagrams show the order of messages passed between objects, services, or users — making them essential for API design, debugging, and architectural documentation.

Key Features

• Lifeline columns for participants (actors, systems, services)
• Activation bars showing when each participant is active
• Message arrows for synchronous and asynchronous calls
• Return message indicators with labeled response types
• Loop and conditional fragment zones for complex interaction patterns

How to Use

1. Define your participants in the header row — add a shape (rectangle or stick figure) for each actor or system, connected to a vertical lifeline using the Connector tool
2. Draw horizontal message arrows between lifelines in order from top to bottom using the Connector tool — label each arrow with the method or event name using the Text tool
3. Add activation bars (narrow rectangles on the lifeline) to show when a component is processing
4. Use dashed return arrows to show responses — adjust arrow style in the connector formatting panel
5. Use the Mermaid tool to render sequence diagrams from code syntax if your team prefers a code-first workflow

Benefits

Sequence diagrams turn invisible system behavior into a readable story. When every engineer on the team can see how components talk to each other, design reviews are faster and bugs are easier to trace.