Sequence Diagram Maker
A sequence diagram shows messages between participants in time order, making calls, replies, and alternative paths visible in one interaction.
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Sequence diagram examples
Open a finished example instantly. Edit the prompt to generate your own version.
A sequence diagram shows messages between participants in time order, making calls, replies, and alternative paths visible in one interaction. Open a finished example below, or describe your own sequence diagram. Free, no signup; hourly fair-use limits apply.
How to create a sequence diagram
Define the scope
Describe one interaction from start to finish rather than your entire application.
Describe the important details
Use concrete message labels such as submit credentials, load account, and return token.
Review and download
Trace the relationships against your requirements, correct the prompt as needed, and download SVG or PNG.
Practical sequence diagram tips
Describe one interaction from start to finish rather than your entire application. Name the participants first: a person, browser, application server, authentication provider, or database. Then list the messages in order, including the response that returns to the caller. This makes a sequence diagram useful for reviewing an API contract, documenting login, or explaining a background worker lifecycle.
Use concrete message labels such as submit credentials, load account, and return token. Distinguish a request from its reply, and describe the condition for each alternative outcome. A successful login and an invalid-password response belong in an alternative fragment rather than being drawn as if both happen during the same run. Activation bars show when a participant is processing an operation; they are not measurements of elapsed time.
The examples cover object creation and destruction, a credential check with a failure branch, and an OAuth authorization-code exchange. Open one to see the rendered diagram immediately, then change the prompt for your own participants and messages. When reviewing the result, trace every response back to the request that caused it and verify that security-sensitive messages go to the correct party. A diagram documents the interaction you describe; it does not test an implementation or prove a protocol is secure. Download SVG for documentation that must stay sharp, or PNG for a quick review slide.
Frequently asked questions
What is the difference between a sequence diagram and a flowchart?
A sequence diagram follows messages across named participants over time. A flowchart follows steps and decisions in a process without requiring participant lifelines.
Can I show success and failure in one diagram?
Yes. Describe the condition for each outcome and request an alternative fragment, such as valid credentials versus an authentication error.
What do activation bars mean?
They show when a participant is executing an operation. Their height is illustrative and does not measure actual response time.
Can I start from an example without generating?
Yes. Click an example to load its rendered DSL immediately. Edit the prompt and generate when you want a different interaction.
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