Use Case Diagram Maker

A use case diagram maps the goals external actors can achieve through a system, with a boundary separating users from the software they use. Open a finished example below, or describe your own use case diagram. Free, no signup; hourly fair-use limits apply.

Start by naming the system and the people or external services that interact with it. An actor is a role, not a particular employee: Customer, Librarian, and Payment Gateway describe responsibilities at the boundary. Then list goals using short verb phrases such as withdraw cash, borrow book, or place order. Keep internal implementation details out of this first view so stakeholders can discuss what the system must do.

The system boundary is the rectangle around the use cases. Human actors and external services sit outside it. A line between an actor and a goal shows participation rather than a chronological step. When one behavior is always required by another, an include relationship can make that shared behavior explicit. An extend relationship describes conditional additional behavior; it should not be used simply because two goals are related.

The ATM example highlights actors around a small system, the bookstore example adds shared checkout behavior, and the library example separates reader and librarian responsibilities. Open a finished example, then replace its goals with your own requirements. Check that every actor has a meaningful interaction and that the boundary does not accidentally include an outside service. Use a sequence diagram when you need the order of messages, and a class diagram when you need data structures. This view is for scope and requirements, not a detailed program flow or a complete specification by itself.