What is ClusterFuzzLite used for?

ClusterFuzzLite is Google's Apache-licensed continuous fuzzing tool that runs in CI to catch bugs in pull requests and run longer batch fuzzing for several languages. It is a good fit for catching vulnerabilities before code is merged and adding fuzz testing to existing CI pipelines.

Is ClusterFuzzLite open source?

Yes. ClusterFuzzLite is open source under the Apache-2.0 licence. Its source code is on GitHub at google/clusterfuzzlite.

Is ClusterFuzzLite free?

Yes. ClusterFuzzLite is open source, so the software itself is free to use.

What are some alternatives to ClusterFuzzLite?

Similar open-source tools in the Testing & QA category include github-action-benchmark, k6 and Bencher. SaaS products in the same category include Codecov, Coveralls and Cypress Cloud.

Is ClusterFuzzLite actively maintained?

The most recent commit to ClusterFuzzLite was on 12 February 2026. The project has 537 stars on GitHub.

ClusterFuzzLite: open-source testing & QA

About ClusterFuzzLite

ClusterFuzzLite is a continuous fuzzing solution from Google that runs inside continuous integration workflows to find vulnerabilities earlier. It is based on ClusterFuzz and is aimed at projects that want fuzz testing as part of normal code review, with only a few lines of configuration.

It supports quick fuzzing of code changes, so bugs can be caught in pull requests before they land, and offers downloadable crashing test cases. Longer-running batch fuzzing finds deeper issues asynchronously and builds a corpus that code-change fuzzing can reuse. Coverage reports show which parts of the code are fuzzed, and the functionality is modular so teams adopt only the features they need.

Supported languages are C, C++, Java and other JVM languages, Go, Python, Rust and Swift. It works with GitHub Actions, GitLab, Google Cloud Build and Prow, with more CI systems in progress. ClusterFuzzLite is released under Apache-2.0, with documentation on the project site and a mailing list for announcements.

Key features

Fuzzing of pull requests in CI
Downloadable crashing test cases
Continuous batch fuzzing for deeper bugs
Coverage reports for fuzzed code
Modular features you can pick and choose
Works with GitHub Actions and GitLab

Good fit for

→Catching vulnerabilities before code is merged
→Adding fuzz testing to existing CI pipelines

Tags: fuzzing; security; ci; continuous-integration; fuzz-testing; vulnerabilities; github-actions; devops

ClusterFuzzLite: questions and answers

What is ClusterFuzzLite used for?: ClusterFuzzLite is Google's Apache-licensed continuous fuzzing tool that runs in CI to catch bugs in pull requests and run longer batch fuzzing for several languages. It is a good fit for catching vulnerabilities before code is merged and adding fuzz testing to existing CI pipelines.
Is ClusterFuzzLite open source?: Yes. ClusterFuzzLite is open source under the Apache-2.0 licence. Its source code is on GitHub at google/clusterfuzzlite.
Is ClusterFuzzLite free?: Yes. ClusterFuzzLite is open source, so the software itself is free to use.
What are some alternatives to ClusterFuzzLite?: Similar open-source tools in the Testing & QA category include github-action-benchmark, k6 and Bencher. SaaS products in the same category include Codecov, Coveralls and Cypress Cloud.
Is ClusterFuzzLite actively maintained?: The most recent commit to ClusterFuzzLite was on 12 February 2026. The project has 537 stars on GitHub.