Fuzzilli

Input—per 1M tokens

Output—per 1M tokens

Context—tokens

WeightsClosed

About

Fuzzilli is ranked #16 of 27 in fuzz testing software on Inferse. It runs on Linux, macOS, Self-hosted.

Compared on fuzz testing software

Input generation methods: mutation, generation, hybridgithub.com
Target types: JavaScript programs and JavaScript engines/interpretersgithub.com
Coverage guidance: Yesgithub.com
Crash triage: Yesgithub.com
Execution mode: hybridgithub.com
Supported languages: JavaScriptgithub.com
CI/CD support: Yesgithub.com

Facts

What it does: Fuzzilli is a coverage-guided fuzzer for dynamic language interpreters, built around a custom intermediate language called FuzzIL that can be mutated and translated to JavaScript.github.com · 3 Oct 2026
Mutations: Its documented mutators can change data flow, generate or splice code, combine corpus programs, and modify operation parameters.github.com · 3 Oct 2026
Fuzzer components: The listed components include a mutation fuzzer, script runner, corpus, environment, minimizer, evaluator, and lifter.github.com · 3 Oct 2026
Execution: Fuzzilli uses a read-eval-print-reset-loop mode in which a modified target engine accepts scripts over pipes or shared memory, executes them, resets, and waits for the next script.github.com · 3 Oct 2026
Scaling: Multiple instances can synchronize within one process or over a TCP-based protocol, allowing scaling across cores and machines.github.com · 3 Oct 2026
Supported targets: The repository lists JavaScriptCore, JerryScript, QuickJS, QtJS, Serenity, SpiderMonkey, V8, XS, Duktape, and njs target directories.github.com · 3 Oct 2026
Build requirements: The usage instructions call for compiling a supported JavaScript engine with coverage instrumentation using clang 4.0 or later, then building Fuzzilli with Swift Package Manager.github.com · 3 Oct 2026
Deployment: The project says Fuzzilli and supported engines can be built and run inside Docker and on Google Compute Engine.github.com · 3 Oct 2026
Cloud tooling: Its Cloud directory contains Docker scripts and files, Google Compute Engine setup and teardown scripts, and rudimentary crash triaging.github.com · 3 Oct 2026
Security results: The repository’s bug showcase lists security issues found with Fuzzilli across engines including WebKit/JavaScriptCore, SpiderMonkey, V8, Duktape, JerryScript, and Hermes.github.com · 3 Oct 2026
Security disclosure: The project asks users to send a short note, possibly with a CVE number, or open a pull request to have a vulnerability found with Fuzzilli considered for the bug showcase.github.com · 3 Oct 2026
License: The repository identifies its license as Apache-2.0.github.com · 3 Oct 2026
Support status: The repository states that Fuzzilli is not an officially supported Google product.github.com · 3 Oct 2026
Intended users: The project describes Fuzzilli as a tool for fuzzing dynamic language interpreters and invites patches and other contributions.github.com · 3 Oct 2026