JUnit 5 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

Category standard

JUnit Team · since 2017

Category standard

Chromatic / OSS community · since 2016

• Universal support across IDEs, build tools and CI in the Java ecosystem.
• The extension model replaced JUnit 4's runners and rules with something composable.
• Pairs cleanly with Mockito, AssertJ, Spring Test and Testcontainers.

• 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.

• Java verbosity persists — expect more lines per test than in Python or JavaScript.
• Parallel execution is opt-in and still occasionally surprising.
• Mixed JUnit 4 and 5 codebases need the vintage engine and stay confusing for years.

• 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.

Every Java and Kotlin project on the JVM.

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