Nothing close enough? Start from a blank sequence diagram → Describe it in one paragraph.
How to use a sequence diagram template.
- 01List the participants
Name the actors and systems — user, client app, auth server, resource API — each becomes a lifeline.
- 02Sequence the messages
Describe the requests and responses in order; the AI draws the arrows and return messages.
- 03Add the failure path
Use an alt fragment to show what happens when credentials or tokens are invalid.
- 04Share for review
Export or share the diagram for security review, API documentation, or onboarding.
Questions about sequence diagram templates
Why diagram an authentication flow as a sequence diagram?
Authentication depends on the precise order of token issuance, validation, and refresh between multiple parties. A sequence diagram shows that ordering and the failure branches clearly.
What is the OAuth 2.0 authorization code flow?
The most common OAuth flow: the app redirects the user to an auth server, receives an authorization code, then exchanges that code (plus a client secret) for an access token at a back-channel endpoint.
How do I show error handling in a sequence diagram?
Use an alt (alternative) combined fragment to split the success and failure paths, or an opt fragment for optional behavior like a token refresh.