UML Diagram StudioUML Studio

Behavioral UML

Sequence Diagram Maker

Draw a sequence diagram for auth flows, service calls, and feature interactions. Start from the template, keep one happy path clear, then add error branches if needed.

Features

  • Live editor for sequence diagram maker
  • Starter template included on the page
  • PNG and SVG export
  • No install required

Need a blank canvas? Open the full UML studio.

What you can model

Sequence diagrams show participants as lifelines and messages as arrows over time. Use them for feature interactions, service calls, and any flow where order matters more than static structure.

How to use this maker

Declare actors and participants, add messages in call order, use alt or loop fragments when branches matter, watch the preview, then export PNG or SVG.

Notation that matters

Solid arrows usually mean synchronous calls. Dashed arrows often show returns. Activation bars mark when work is happening. Name messages after real operations so readers can map them to code. If you already have steps in a doc, turn each step into a short message top to bottom.

Keep the diagram readable

One happy path per diagram when possible. Split deep error handling onto a second view. Use the API sequence diagram maker for HTTP hop documentation, and an activity diagram when the story is a procedure rather than message order.

Frequently asked questions

Is this sequence diagram maker free?

Yes. Edit, preview, and export without a subscription.

Sequence diagram or activity diagram?

Use sequence when message order between participants matters. Use activity when the focus is workflow steps and decisions.

Need an API-focused sequence?

Open the API sequence diagram maker when the story is specifically HTTP request and response hops.

Related tools

Browse the full UML diagram tools directory or return to the UML diagram hub.