# google/AFL

american fuzzy lop - a security-oriented fuzzer

Repository: https://github.com/google/AFL
Canonical: https://ross.abutalabs.com/products/afl
Homepage: https://lcamtuf.coredump.cx/afl/
Language: C
License: Apache-2.0
License Family: permissive
Archived: true
Last push: 2021-07-05T14:02:41+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 2596, "days_push": 1885, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4205, forks 671 (observed 2026-08-28T04:08:39.030258+00:00)

## What it is
American Fuzzy Lop (AFL) is a security-oriented, coverage-guided fuzzer that uses compile-time instrumentation and genetic algorithms to discover inputs triggering new program states and crashes. It is the original classic fuzzer by Michal Zalewski, now largely superseded by the community-maintained AFL++ fork.

## Use cases
- fuzz a file parsing library to find crashes
- find memory corruption bugs in a C program
- generate a seed corpus for further security testing
- minimize a crashing test case to its smallest form
- fuzz image decoders or compression libraries for vulnerabilities

## When to choose
- you need a proven, simple, low-configuration coverage-guided fuzzer
- you want the classic AFL instrumentation workflow or are following older tutorials
- you need crash triage tools like test case minimization

## When to avoid
- you want active development and modern features - use AFL++ instead
- you need structured grammar-aware or in-process fuzzing
- you target platforms beyond Linux/macOS

## Facets
- artifact type: cli-tool
- maturity: maintenance
- function: fuzzing, testing, security
- domain: security, developer-tools, testing
- platform: cli
- tags: fuzzer, coverage-guided, genetic-algorithm, instrumentation, vulnerability-discovery, afl, linux, macos

## Member repositories
- google/AFL (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:39.030258+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:22:31.138117+00:00, confidence not recorded.
  - readme: https://github.com/google/AFL (fetched 2026-08-28T04:08:39.030258+00:00, sha d75cbfed2c4e)
  - homepage: https://lcamtuf.coredump.cx/afl/ (fetched 2026-08-29T09:12:52.470147+00:00, sha 2ff5dfb5ff44)
  - site_page: https://lcamtuf.coredump.cx/afl/releases?O=D (fetched 2026-08-29T09:12:52.481907+00:00, sha cf919af88206)
- Data as of 2026-08-30T08:39:29.467469+00:00.