A free use case diagram maker that shows who can do what
- Free
- No sign-up
- Works offline
Put the actors outside the boundary and the use cases inside, then press Present and walk through what each actor is actually allowed to do.
Present reveals your use case diagram one step at a time, on its own.
A use case diagram answers one question before a line of code is written: who uses this system, and what can each of them do? Free to draw, no sign-up, kept in your browser.
It is deliberately shallow. A use case diagram is a contents page for behaviour, not a description of it — which is why it stays readable when a requirements document has long since stopped being read.
Actors, use cases, and the system boundary
An actor is anyone or anything outside the system that interacts with it — a customer, an administrator, a payment gateway, a scheduled job. A use case is a goal that actor can achieve, written as a verb phrase: Withdraw cash, not Cash withdrawal screen.
The system boundary is the box around the use cases, and it is the most useful line on the diagram: everything inside is your responsibility, everything outside is somebody else's. Arguments about scope usually resolve themselves once that box is drawn.
Two relationships are worth knowing. Include means a use case always performs another one — Withdraw cash includes Authenticate. Extend means it sometimes does, under a condition. Most diagrams overuse both; if in doubt, leave them out and let the use cases stand alone.
Write use cases as goals, not as screens
The failure that makes a use case diagram useless is naming the boxes after the user interface. Login page, Dashboard and Settings screen describe a design that has not been agreed yet, and they will be wrong the moment it changes.
Transfer funds, Dispute a transaction and Set a spending limit describe what a person is trying to achieve, which stays true across every redesign.
Present it actor by actor
Press Present and the diagram builds one actor at a time with the use cases they can reach. That is the clearest way to run a scoping review — and a surprisingly effective way to spot a missing permission, because the room sees exactly what each role can do before moving on.
How to make a use case diagram, start to export
Open the editor, draw the system boundary, then place a use case inside it for each goal. Add the actors outside and connect each to the use cases they can reach. Add include and extend only where they genuinely apply, then export or present.
Free, private, and offline
Diagramium is free and there is no paid tier. Draw, present and export PNG or SVG without an account; a free account unlocks the animated export formats — GIF, video and animated SVG.
Your diagram is stored in your own browser, not on a server. It keeps working with the network off, and nothing is uploaded unless you choose to publish it.
Frequently asked questions
Is this use case diagram maker free?
Diagramium is free and there is no paid tier. Draw, present and export PNG or SVG without an account; a free account unlocks the animated export formats — GIF, video and animated SVG.
What is the difference between include and extend?
Include means the behaviour always happens as part of the use case; extend means it happens only under a condition. If you are unsure which applies, the diagram is usually clearer without either.
Can an actor be another system?
Yes. A payment gateway, an identity provider or a nightly batch job are all actors — anything outside your boundary that starts or takes part in an interaction.
How detailed should a use case diagram be?
One page, usually under a dozen use cases. It is a contents page for behaviour; the detail belongs in the use case descriptions, or in a sequence diagram for the ones worth walking through.
Is a use case diagram still worth drawing?
For agreeing scope and permissions with non-technical stakeholders, yes — it is the only UML diagram most of them will read. As a substitute for written requirements, no.
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