ClusterFuzz vs Csmith

ClusterFuzz is open-source infrastructure for finding security and stability problems in software through fuzzing. It supports coverage-guided engines libFuzzer, AFL++, and Honggfuzz, alongside blackbox fuzzing. Its workflow can find crashes, group duplicates, minimize testcases, use bisection to locate regressions, and verify fixes. It can also file, triage, and close bugs automatically. Google uses ClusterFuzz across its products and as the fuzzing backend for OSS-Fuzz. The system is designed to run on clusters of any size; Google’s instance runs on 30,000 VMs. Production deployments use Google Cloud services, including App Engine, Cloud Storage, Cloud Datastore, Cloud Pub/Sub, BigQuery, and Stackdriver Logging and Monitoring. Local instances are supported on Linux and macOS, with some BigQuery- and Stackdriver-dependent features disabled. Although the overview mentions Monorail and Jira as examples, the architecture currently supports only Chromium-hosted Monorail. The software runs on Linux, macOS, and Windows and is licensed under Apache-2.0. Its listed price is free.

Csmith is a free, open-source generator of random C programs for finding compiler bugs through differential testing. Its output avoids undefined behavior and includes statistics for each generated program. A documented workflow compiles programs with GCC and Clang, then compares their outputs to identify differences. The tool can also create material for a C test suite when users do not want to write one themselves. Command-line options shown by csmith -h and csmith -hh customize random generation. Csmith runs locally on Linux and Windows. Ubuntu source builds require g++, CMake, and m4, followed by CMake and make; Windows builds are documented with Visual Studio or WSL. The project says it should build on most modern machines with a C++ compiler. Generated programs may loop indefinitely, so execution timeouts are recommended. The repository includes a COPYING license file. Bug reports and suggestions go through GitHub issues, with discussion on a mailing list; maintainers warn replies may be delayed.