NUnit

Name: NUnit
Author: .NET Foundation

The long-standing .NET test framework with the richest assertion set.

Unit & ComponentOpen sourceSelf-hostable

What it is

NUnit is the oldest of the .NET unit testing frameworks and remains widely used, with a comprehensive constraint-based assertion model, flexible setup/teardown attributes and strong parameterised-test support. It runs everywhere .NET runs.

Best for

Existing .NET codebases already standardised on NUnit.

Where it is strong

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

Where it falls short

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.

Pricing

Free and open source

Open source

Free tier: Everything, self-hosted

What drives the bill: Free and open source. You pay in engineering time and CI minutes.

Check current pricing on .NET Foundation’s site

Figures are indicative and were last reviewed August 2026. Vendors change pricing often; confirm before you commit.

Works with

dotnet testVisual StudioAzure DevOpsMoqJenkins

What people who use NUnit say

No reviews of NUnit yet. If you have used it in anger, yours would be the first.

Alternatives to NUnit

If NUnit is not the right fit, these solve the same problem differently.

xUnit.net

Unit & Component

The modern .NET testing framework, and the one Microsoft's templates default to.

Open sourceSelf-host

NUnit vs xUnit.net