Best Free Fuzz Testing Tools of 2024

Atheris is an engine for Python fuzzing that uses coverage-guided fuzzing. It supports fuzzing Python code as well as native extensions written in CPython. Atheris is based off libFuzzer. Atheris is a tool that can be used for fuzzing native code to find additional bugs. Atheris supports Linux 32- and 64-bit and Mac OS X with Python versions 3.6-3.10. It comes with an integrated libFuzzer that is suitable for fuzzing Python code. If you want to fuzz native extensions you may have to build Atheris from source in order to match the libFuzzer versions. Atheris relies upon libFuzzer which is distributed along with Clang. Apple Clang does not come with libFuzzer. You'll have to install a different version of LLVM. Atheris is based upon a coverage-guided, mutation-based fuzzer called LibFuzzer. This has the benefit of not requiring a grammar definition to generate inputs. It makes its setup easier. The disadvantage is that the fuzzer will have a harder time generating inputs for complex data types.

Wfuzz is a framework for automating web application security assessments. It could help you secure web applications by finding web application vulnerabilities and exploiting them. You can also run the Wfuzz image from Docker. Wfuzz works on the simple principle that it replaces all references to the fuzz keyword by the value of the payload. In Wfuzz, a payload is a data source. This simple concept allows for any input to be injected into any field of an HTTP Request, allowing for complex web security attacks to be performed in different web application components, such as parameters and authentication, forms, directories/files or headers. Plugins are used to support Wfuzz's vulnerability scanner for web applications. Wfuzz's modular structure makes it easy to contribute, even for the newest Python programmers. The process of creating plugins is easy and takes only a few moments.

Fuzzapi uses API Fuzzer for REST API pentesting. It also provides UI solutions to gem.

API Fuzzer is a tool that allows you to test API attributes by using pentesting techniques. It also lists vulnerabilities. API Fuzzer gem takes an API request and returns all vulnerabilities that are possible. IDOR, API rate limiting vulnerabilities, open redirect flaws, information disclosure flaws and info leakage via headers.

Wapiti is an application vulnerability scanner. Wapiti is a web application vulnerability scanner that allows you to audit your website or web application's security. It crawls the pages of the deployed web application, looking for scripts or forms where it could inject data. Wapiti, once it has a list of URLs and forms, as well as their inputs (inputs), acts like a "fuzzer" by injecting payloads into a script to see if it is vulnerable. Search for potentially harmful files on the server. Wapiti can be used to launch attacks using both GET HTTP and POST methods. It can also inject payloads into filenames. When an anomaly is detected (for example, 500 errors and timeouts), warnings are raised. Wapiti can distinguish between reflected and permanent XSS vulnerabilities. Creates vulnerability reports in different formats (HTML XML JSON TXT CSV).

Echidna is a Haskell program designed for fuzzing/property-based testing of Ethereum smart contracts. It uses sophisticated grammar based fuzzing campaigns, based on an ABI contract, to falsify user defined predicates or Solidity statements. Echidna was designed with modularity in the mind. It can be easily expanded to include new mutations, or test specific contracts for specific cases. It generates inputs that are tailored to your code. Use optional corpus collection, mutation and guidance to find deeper bugs. Powered by Slither, to extract useful information prior to the fuzzing campaigns. Source code integration for identifying which lines have been covered after the fuzzing campaign. Interactive terminal UI with text-only output or JSON. Automatic test case minimization to speed up triage. Integration into the development workflow is seamless. Reporting of maximum gas usage during the fuzzing campaign. Support for the complex contract initialization process with Etheno, Truffle.

Syzkaller is a kernel fuzzer that uses coverage to guide the fuzzing process. Supports FreeBSD Fuchsia gVisor Linux, NetBSD OpenBSD and Windows. Initially, syzkaller focused on Linux kernel fuzzing, but it is now being extended to other OS kernels. When syzkaller detects a crash in a VM, it will start the process to reproduce the crash. It will, by default, use 4 VMs in order to reproduce the crash. Then it will minimize the program which caused the crash. This could stop the fuzzing as all the VMs may be busy reproducing crashes. The time it takes to reproduce a crash can vary from a few seconds up to an entire hour, depending on how easily reproducible the crash is or if it cannot be reproduced at all.