ClusterFuzz

No phone app

6.4No. 5 of 27
in Fuzz Testing Software
  • Recognised40% of the score20
  • Phone app26% of the score0
  • Documented20% of the score98
  • Free plan14% of the score100
Free plan
Yes
Runs on
Linux, Mac, self-hosted, Web, Windows

Summary

ClusterFuzz is open-source infrastructure that uses fuzzing to find security and stability issues in software. It supports coverage-guided fuzzing with libFuzzer, AFL++, and Honggfuzz, as well as blackbox fuzzing. Its workflow can find crashes, group duplicate reports, minimize testcases, bisect revisions to locate regressions, and verify fixes. It can also automate bug filing, triage, and closure. Google uses ClusterFuzz across its products and as the fuzzing backend for OSS-Fuzz; the project says it can run on clusters of any size. Production deployments depend on Google Cloud services, including App Engine, Cloud Storage, Cloud Datastore, Cloud Pub/Sub, BigQuery, and Stackdriver. Local instances can use Google Cloud emulators, but features depending on BigQuery and Stackdriver are disabled, and local instances are supported only on Linux and macOS. ClusterFuzz runs on Linux, macOS, and Windows. Its repository is licensed under Apache-2.0, and the architecture currently supports Chromium-hosted Monorail as its bug tracker.

Who it is for

ClusterFuzz suits software teams that need automated fuzzing and crash triage across Linux, macOS, or Windows. Local deployment is an option for Linux and macOS users; production deployment depends on Google Cloud services.

What is good

  • Supports libFuzzer, AFL++, and Honggfuzz.
  • Minimizes testcases and bisects regressions.
  • Can automate bug filing and triage.
  • Apache-2.0 licensed and free.

What to know first

  • Production deployments depend on Google Cloud services.
  • Local instances are supported only on Linux and macOS.
  • Local BigQuery- and Stackdriver-dependent features are disabled.
  • Architecture currently supports Chromium-hosted Monorail as its bug tracker.

Verdict

ClusterFuzz combines fuzzing with crash processing and bug-tracker automation, and it is available under an open-source license. Deployment requirements differ between production and local use, and local users should note the operating-system and feature limitations.

ClusterFuzz plans and pricing

All plans
ClusterFuzz (open source) Free Apache-2.0 licensed software · production deployment depends on Google Cloud services github.com · 2 Oct 2026

Compared on fuzz testing software

Input generation methods
mutation, generation, hybridgoogle.github.io
Target types
binary formats, HTML, JavaScript, browser DOM, native programsgoogle.github.io
Coverage guidance
Yesgoogle.github.io
Crash triage
Yesgoogle.github.io
Execution mode
hybridgoogle.github.io
Supported languages
C, C++, Rust; potentially other LLVM-based languagesgoogle.github.io
CI/CD support
Yesgoogle.github.io

Facts

Purpose
ClusterFuzz is scalable fuzzing infrastructure that finds security and stability issues in software.google.github.io · 2 Oct 2026
Google and OSS-Fuzz
Google uses ClusterFuzz to fuzz all Google products and as the fuzzing backend for OSS-Fuzz.google.github.io · 2 Oct 2026
Scalability
ClusterFuzz can run on any size cluster; Google’s instance runs on 30,000 VMs.google.github.io · 2 Oct 2026
Fuzzing engines
It supports libFuzzer, AFL++, and Honggfuzz for coverage-guided fuzzing, plus blackbox fuzzing.github.com · 2 Oct 2026
Crash processing
Features include crash deduplication, testcase minimization, and regression finding through bisection.github.com · 2 Oct 2026
Bug automation
ClusterFuzz can automatically file, triage, and close bugs for issue trackers such as Monorail and Jira.github.com · 2 Oct 2026
End-to-end workflow
The infrastructure finds and triages crashes, minimizes reproducers, bisects revisions, and verifies fixes.google.github.io · 2 Oct 2026
Supported operating systems
ClusterFuzz runs on Linux, macOS, and Windows.google.github.io · 2 Oct 2026
Cloud dependencies
Production deployments use Google Cloud services including App Engine, Cloud Storage, Cloud Datastore, Cloud Pub/Sub, BigQuery, and Stackdriver Logging and Monitoring.google.github.io · 2 Oct 2026
Local deployment
ClusterFuzz can run locally with Google Cloud emulators, but BigQuery- and Stackdriver-dependent features are disabled and local instances are supported only on Linux and macOS.google.github.io · 2 Oct 2026
Bug tracker limit
The only bug tracker currently supported by the architecture is Chromium-hosted Monorail.google.github.io · 2 Oct 2026
Web interface
The web interface includes Testcases, Fuzzer Statistics, Crash Statistics, Upload Testcase, Jobs, and Configuration pages.google.github.io · 2 Oct 2026
Access control
Privileged users can access security bugs, upload fuzzers and corpora, and create jobs, while administrators also manage configuration and permissions.google.github.io · 2 Oct 2026
Authentication
ClusterFuzz supports various authentication providers using Firebase.github.com · 2 Oct 2026
Security reporting
The Google Security Team asks vulnerability reporters to use g.co/vulnz and says reports are processed within a day with responses within a week depending on severity.github.com · 2 Oct 2026
Support
Users can file a GitHub issue to ask questions, request features, or ask for help.github.com · 2 Oct 2026
License
The ClusterFuzz repository is published under the Apache-2.0 license.github.com · 2 Oct 2026
Crash handling
It provides crash deduplication, automatic bug filing and triage, testcase minimization, and regression finding through bisection.google.github.io · 2 Oct 2026
Integrations
The overview lists Monorail and Jira as example issue trackers and Firebase for authentication; the architecture page says Monorail is currently the only supported bug tracker.google.github.io · 2 Oct 2026
Cloud requirements
Production deployments run on Google Cloud Platform and depend on services including App Engine, Cloud Storage, Cloud Datastore, Cloud Pub/Sub, BigQuery, and Stackdriver Logging and Monitoring.google.github.io · 2 Oct 2026
Other compute
Fuzzing bots can run on machines outside Google Compute Engine, including machines from another cloud provider, if they can access the required Google services.google.github.io · 2 Oct 2026
Local limitations
Local instances can run without Google Cloud emulators, but some features that depend on BigQuery and Stackdriver are disabled.google.github.io · 2 Oct 2026
Supported systems
ClusterFuzz runs on Linux, macOS, and Windows, while local instances are supported only on Linux and macOS.google.github.io · 2 Oct 2026
Security issues found
The project repository reports that, as of February 2023, ClusterFuzz helped identify and fix over 8,900 vulnerabilities across projects integrated with OSS-Fuzz.github.com · 2 Oct 2026

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