Requirement Diagram
Free Online Requirement Diagram Maker
A requirement diagram shows requirements, the system elements that meet them, and the relationships between them, such as satisfies and verifies. It comes from SysML and is used to prove that every requirement is covered by a design element and checked by a test.
Write each requirement with its id, text, risk and how it is verified, then link it to the elements that satisfy and verify it.
Last updated: · Mermaid v11
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When to use requirement diagram
Traceability for audits
Show which component satisfies each requirement and which test verifies it, in a form that sits in the repository and changes with the code.
Specification reviews
Give reviewers a picture of the requirements and their risk levels alongside the written spec, so gaps are easier to spot.
Systems engineering
Sketch SysML-style requirement structures without a modelling tool, then refine them as the design matures.
Key syntax
requirementDiagramDeclare the diagramrequirement name { ... }A requirement with id, text, risk, verifymethodrisk: highlow, medium or highverifymethod: testanalysis, inspection, test or demonstrationelement name { type: service }A system elementa - satisfies -> bA relationship (also verifies, traces, derives, refines)How to create a requirement diagram with Mermaid
Open the FlowViz editor and type requirementDiagram on the first line.
Declare a requirement block with id, text, risk and verifymethod.
Declare the system elements with element name { type: ... }.
Link them: element - satisfies -> requirement, test - verifies -> requirement.
Use a more specific type such as performanceRequirement where it fits.
Export as SVG or PNG, or copy a share link.
Frequently asked questions
What is a requirement diagram used for?
Tracing requirements to the parts of a system that satisfy them and the tests that verify them. It follows the SysML requirement diagram, so it suits regulated or safety-related work where traceability is required.
Which requirement types are there?
requirement, functionalRequirement, interfaceRequirement, performanceRequirement, physicalRequirement and designConstraint. Each takes an id, text, risk (low, medium, high) and verifymethod (analysis, inspection, test, demonstration).
Which relationships can I draw?
contains, copies, derives, satisfies, verifies, refines and traces, written as source - satisfies -> target.
Is the FlowViz requirement diagram maker free?
Yes. It is free with no account, and you can export SVG or PNG or share the diagram as a link.
Start diagramming now
No signup. No install. Just open the editor and start writing.