NUnit vs Storybook

Free and open source

Free and open source

Free and open source. You pay in engineering time and CI minutes.

Storybook itself is free. Chromatic, the hosted visual-review service from the same team, is a separate paid product.

Everything, self-hosted

Everything, self-hosted

Widely used

.NET Foundation · since 2002

Category standard

Chromatic / OSS community · since 2016

• The most expressive built-in assertion library in .NET.
• Familiar attribute model for teams migrating from older frameworks.
• Very stable, very long-lived.

• One artefact serves as documentation, visual baseline and interaction test.
• Design-system teams get a shared reference that designers can actually open.
• Rich addon ecosystem for accessibility, viewport and state manipulation.

• Shared test-class instances mean state can leak between tests unless you are careful.
• New Microsoft templates default to xUnit, so it is drifting from the mainstream.
• Attribute-heavy style feels dated.

• Meaningful configuration and maintenance overhead; a neglected Storybook rots fast.
• Build times on large component libraries get long.
• Stories drift from production usage unless discipline is enforced.

Existing .NET codebases already standardised on NUnit.

Teams maintaining a design system or a large shared component library.