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AFL++

Coverage-guided fuzzer, successor to AFL

Community-maintained successor to american fuzzy lop with faster instrumentation, custom mutators and QEMU, Frida and Unicorn modes for binaries.

Open sourceAGPL-3.0-only
Visit website View repository Docs
Homepage of AFL++
Official website (aflplus.plus), captured by ThreatWire.

What AFL++ does

AFL++ mutates inputs and keeps those that reach new code paths, measured through compile-time instrumentation (LLVM, GCC) or binary-only modes based on QEMU, Frida and Unicorn. It adds many improvements over the original AFL, such as CmpLog, power schedules and custom mutator APIs.

It is used in research and in continuous fuzzing services such as OSS-Fuzz to find memory safety bugs and crashes.

Key features

  • LLVM and GCC instrumentation
  • QEMU, Frida and Unicorn binary-only modes
  • CmpLog and other comparison-solving features
  • Custom mutator API
  • Parallel and distributed fuzzing

Licence

AGPL-3.0-only · GNU AGPL v3 · Open source

Checked by ThreatWire against the repository's licence file on 2026-10-20. GitHub detects: AGPL-3.0.

Security of AFL++ itself

No published advisory found for AFL++ in GitHub repository advisories. That does not mean the tool has no vulnerabilities.

Sources: GitHub repository advisories · checked 2026-10-20.

Categories and tags

Fuzzing#coverage-guided#fuzzer#c#binary#afl#afl-fuzz#afl-fuzzer#fuzzing#fuzz-testing

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