UML Diagram StudioUML Studio

Behavioral UML

API Sequence Diagram Maker

Document an API call path with a sequence diagram: client, gateway, services, and status codes that matter. Adapt the starter hops to your endpoint, then export for specs.

Features

  • Live editor for api sequence diagram
  • 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

API sequence diagrams show hop-by-hop request and response paths: who receives the HTTP call, what internal call follows, and what status returns. They help frontend, backend, and QA agree on a flow before implementation drifts.

How to use this maker

Name the client and services, write one message per hop, add an alt fragment for error statuses, preview, then export into an API spec or RFC.

Notation that matters

Label messages with methods and paths when useful (GET /v1/users/42). Show return statuses on the way back. Keep participant aliases short so the diagram stays readable on a wiki page.

Keep the diagram readable

Prefer one diagram per important flow. Bundle trivial CRUD into a shared pattern note when hops are identical. Use the general sequence diagram maker for non-HTTP collaborations, and a microservices diagram for topology without message order.

Frequently asked questions

Is this API sequence diagram maker free?

Yes. Create and export online without a paid plan.

How is this different from the sequence diagram maker?

This page is optimized for API and HTTP flows. The general sequence maker covers broader interaction scenarios.

Should every endpoint get its own diagram?

Prefer one diagram per important flow. Bundle identical CRUD hops into a shared pattern note.

Related tools

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