Verify

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Introduction

Verify simplifies assertions on complex data models and documents. During the assertion phase it serialises the test result and stores it in a file matching the test name; on the next run the result is serialised again and compared, and the test fails if the snapshots differ, meaning either the change is unexpected or the reference snapshot needs updating.

It supports xUnit, NUnit, MSTest, TUnit, Expecto and Fixie. An important change: every version released after 1 September 2026 is covered by an Open Source Maintenance Fee for organisations that generate revenue from the official binaries and NuGet packages, and for government agencies. The source stays open and free, earlier versions are not covered, and from v33 sponsorship is verified at build time by SponsorCheck, which runs inside the build, phones nothing home and issues no licence keys.

The source code is at VerifyTests/Verify on GitHub under the MIT licence, with about 3,500 stars; the most recent commit was on 10 November 2026.

Features

1. Snapshot files: Per-test verified files.
2. Complex object support: Serialises models and documents.
3. Diff tooling: Compare changes.
4. Framework support: Works with major .NET test frameworks.
5. Line-ending handling: Configurable tolerance.

Pros

1. Readable tests: Replace dozens of asserts with a snapshot.
2. Free to use: Open source under the MIT licence, so the core tool costs nothing to use.
3. Actively maintained: The repository had commits as recent as 10 November 2026.
4. Community: About 3,500 GitHub stars.

Cons

1. Maintenance fee: Applies to revenue-generating organisations for new versions.
2. Snapshot churn: Snapshots need review discipline.

Usage and Links (Example)

[Fact]
public Task Order_snapshot()
{
    var order = BuildOrder();
    return Verify(order);
}

Review and accept .received files when changes are intentional.

Resources:

• Verify website

Pricing

Verify’s source is MIT-licensed and free. Versions released after 1 September 2026 require revenue-generating organisations and government agencies to sponsor VerifyTests at a monthly tier matching their size (the Open Source Maintenance Fee); earlier versions are not covered.

Recommended for?

1. .NET teams testing complex outputs such as DTOs, documents and API responses.

Conclusion

Verify is the standard snapshot tool for .NET.

Check whether the maintenance fee applies to your organisation.

On CheckOps, Verify is filed under the Unit testing and Integration testing stages. Related tools listed here include insta, Jest, SnapshotTesting (Point-Free), Fluent Assertions, xUnit.net and NUnit. A short trial on a real project, with your own code, data and pipeline, is usually the fastest way to choose between them, because fit matters more than feature lists. Facts here come from the official site, documentation and repository, checked on 11 November 2026.