01
Open your diagram
Paste PlantUML, import a .puml file or start with a ready-made example.
PLANTUML SEQUENCE DIAGRAM EDITOR
Complex diagram. Clear next step.
Understand a flow before your next review. Find the right message, fold away the details and move between your diagram and PlantUML code.
Free editor. No account needed. Your diagrams stay in this browser.
How it worksThe local editor is ready. Availability of additional features is not yet confirmed.
Already have an account? Your data, deletion and subscription cancellation remain available. Manage account · Support
Sequence + ActivityYour PlantUML source stays intact.puml and SVG export
01 / FROM SOURCE TO A CLEAR FLOW
Open. Focus. Follow.
02
Keep the relevant details
Collapse blocks and focus on a participant. The full source stays intact.
03
Connect the steps
Click a message to find its source. Use the diagram to explain the flow at your review.
02 / AI SCENARIOS
Generate scenarios. Follow each flow.
AI suggests business scenarios from your current diagram. Choose one to highlight its path and play the steps in sequence.
Optional AI requires an account and is available only in supported regions. The local editor works without an account.
Generate → Choose a scenario → Play the steps
See which messages belong to the selected scenario, which branches it follows and how it ends. Your PlantUML source stays unchanged.
Open the checkout exampleSee the flows inside your diagram.
Generate a list of suggested scenarios, with business goals, outcomes and the branches they follow.
Follow one scenario step by step.
Select a generated scenario to highlight its messages. Play the sequence or move through the steps manually.
Make the assumptions visible.
Review the selected conditions and AI assumptions alongside the diagram before using a scenario in a discussion or test case.
AI suggests paths through the branches you have modeled. Review its assumptions; it does not run your system or guarantee test coverage.
03 / EXAMPLE DIAGRAMS
Start with a ready-made diagram.
Sample PlantUML projects you can open, explore and edit.
EXAMPLE
Checkout
Explore an order flow with inventory reservation, payment and a failure branch.
Payment & inventoryExplore exampleEXAMPLE
Passwordless sign-in
Follow a one-time sign-in link through validation, expiry and session creation.
AuthenticationOpen exampleEXAMPLE
Event delivery
Trace webhook retries and see where failed deliveries end up.
Webhooks & retriesOpen exampleA few things to know.
Do I need an account?
You can edit and explore diagrams without signing in. Optional AI scenarios require an account and regional availability.
Where do my diagrams go?
Your diagram library is stored in this browser. Download .puml backups to keep your work. If you choose to generate AI scenarios in a supported region, your diagram source is sent to our AI provider for processing.
How do AI credits work?
Where signup and AI are available, new verified accounts receive 20 credits. A successful generation costs 5 credits.
Which diagrams are supported?
The editor supports PlantUML Sequence and Activity diagrams, with limits on supported constructs. Include and preprocessor directives are not supported by the local engine. AI scenarios work with supported flows only.
How do I back up my work?
Download your .puml files. Browser storage is local to this device and can be removed when you clear site data.
START WITH ONE FLOW
Bring a diagram. Leave with a clearer flow.
Free editor. No account needed.