Csmith vs Jazzer

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.

Jazzer is a free, coverage-guided fuzzer for JVM applications, running in-process and based on libFuzzer. It supports Java, Kotlin, Scala, and Clojure targets, as well as JNI and native libraries. With JUnit 5.9.0 or newer, fuzz tests can run alongside regular unit tests. The @FuzzTest annotation lets Jazzer generate and mutate method inputs, including primitives, strings, arrays, and standard library classes. JUnit fuzz tests can use saved crashing inputs in regression mode or generate and mutate inputs to explore coverage. Built-in sanitizers detect Java security issues such as SSRF, file path traversal, and OS command injection, and provide feedback to guide fuzzing. The README documents use with Maven, Gradle, and Bazel. Jazzer can also run as a standalone binary or through its Java main class. Supported systems are Linux x86_64 and arm64, macOS 12 or newer on x86_64 and arm64, and Windows x86_64. The jazzer-junit package is available on Maven Central, and the repository identifies the project as licensed under Apache-2.0.