Use Case Diagram Generator: From Requirements to UML

A use case diagram is the highest-level view of a system in UML. It shows the people and external systems that interact with it, called actors, and the goals they can achieve, called use cases. It deliberately leaves out screens, data and the order of steps.

That simplicity is why it appears so early in a project and in so many software engineering courses. It gives everyone a shared list of what the system must do before anyone argues about how. A use case diagram generator saves the drawing time so the discussion can start sooner.

Start with the users. Name each kind of user and the main things they want to do, for example "customers search products and place orders". Then name any outside system the software talks to, such as a payment provider, an email service or a government database.

Mention steps that several goals share, like logging in or checking a balance, so the generator can turn them into include relationships. Optional behaviour, such as applying a discount code, becomes an extend relationship. Short, direct sentences work better than a long specification.

Look at the boundary first: actors must stay outside it and use cases inside it. Then check that every actor connects to at least one use case and that each use case is a goal, not a single click. "Pay for Order" is a good use case; "Press Pay Button" is too small.

Next, look at the dashed arrows. An include points from the main use case to the shared step, and an extend points from the optional behaviour to the use case it extends. If a direction looks wrong, fix it in the editor or ask the AI to reverse it.

A use case diagram tells you what the system does, but not how. For the order of messages inside one use case, such as a login or a payment, draw a sequence diagram. For the data behind it, draw an ER diagram, and for the code structure, a class diagram.

This site has a generator for each of those views, and they all produce Draw.io files that open in the same editor. Writing one description and reusing it across diagram types keeps names consistent from requirements to design.