Fuzzilli vs Mayhem

Fuzzilli is a free, open-source, coverage-guided fuzzer for dynamic language interpreters. It represents test programs in FuzzIL, mutates them, and translates them to JavaScript for execution. Its mutators can change data flow or operation parameters, generate or splice code, and combine corpus programs. Components include a mutation fuzzer, script runner, corpus, environment, minimizer, evaluator, and lifter. A target engine runs repeated scripts in a read-eval-print-reset loop, resetting between cases; multiple instances can synchronize within a process or across machines over TCP. Listed target directories include JavaScriptCore, JerryScript, QuickJS, QtJS, Serenity, SpiderMonkey, V8, XS, Duktape, and njs. Setup requires compiling a supported engine with coverage instrumentation using clang 4.0 or later, then building Fuzzilli with Swift Package Manager. Docker and Google Compute Engine tooling are provided. The project supports Linux, macOS, and self-hosted use and identifies its license as Apache-2.0. Its repository says it is not an officially supported Google product. Contributions require a Contributor License Agreement and are reviewed through GitHub pull requests.

Mayhem is a security platform for testing code and APIs and assessing software components in a dashboard. Its fuzzing combines AI-powered, network-aware methods with symbolic execution and triage. For code, it generates tests autonomously to find vulnerabilities and supplies a reproduction and backtrace for each defect. Mayhem for API tests for OWASP Top 10 API weaknesses and supports stateful, agentless testing. Dynamic SBOM reachability analysis helps identify which software components are on the attack surface. The platform produces vendor-neutral SARIF reports and real-time notifications, and lists integrations with tools including GitHub, Jenkins, GitLab, Jira, Slack, CircleCI, Azure DevOps, Google Chat and Travis CI. Deployment options include managed SaaS, private cloud and closed-network installation; command-line tools run on macOS, Linux and Windows. The Mayhem for API free plan allows up to 50 scans per month. Paid API plans cost $236 a month, with additional scans, enterprise features and personalized support; a 30-day trial is listed for paid plans.