googleprojectzero/fuzzilli
A JavaScript Engine Fuzzer observed · 2026-08-28
Health v2 · maintenance only
67/100
- Activity 98
- Release rhythm 8
- Longevity 100
How is this computed?
round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10) — computed 2026-09-03. Adoption (stars, forks) is never an input.
- gap_med: n/a
- age_days: 2723
- days_rel: n/a
- days_push: 13
- n_releases_24m: 0
Adoption not part of the score
2334 stars · 368 forks observed · 2026-08-28
What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded
Fuzzilli is a coverage-guided fuzzer for JavaScript engines, built in Swift by Google Project Zero. It generates test programs via a custom intermediate language (FuzzIL) that is mutated and translated to JavaScript to find interpreter and JIT compiler bugs.
Use cases
- fuzz a JavaScript engine like V8 or SpiderMonkey for security bugs
- find JIT compiler vulnerabilities in interpreters
- discover zero-day bugs in JavaScript runtimes
- run coverage-guided fuzzing campaigns on custom language interpreters
- research semantic correctness of generated test programs
- scale fuzzing across cloud compute instances
When to choose
- you are doing vulnerability research on JavaScript engines or JIT compilers
- you need a coverage-guided, mutation-based fuzzer with a custom IL for dynamic languages
- you want to find deep interpreter bugs that naive fuzzers miss
When to avoid
- you need to fuzz web applications or APIs rather than language interpreters
- you cannot compile the target engine with coverage instrumentation
- you want a simple black-box fuzzer without building Swift toolchains and applying engine patches
Facets
cli-tool · maturity active
fuzzing testing security interpreter compiler security penetration-testing programming-languages developer-tools cli javascript-engine coverage-guided-fuzzing vulnerability-research intermediate-language jit-compiler linux macos docker swift
1 source
- readme: https://github.com/googleprojectzero/fuzzilli · fetched 2026-08-28 · dd35256a4449
Member repositories
| Repository | Role | Health v2 |
|---|---|---|
| googleprojectzero/fuzzilli | main | 67 |
For agents
markdown · JSON · MCP: product_card(name="googleprojectzero/fuzzilli")
Data as of 2026-08-30T08:39:29.467469+00:00 · Report a problem