FYEO Custom Fuzz Testing vs vaf: Side-by-Side Comparison (2026)
Features, pricing, ratings, and pros & cons — compared head-to-head.
FYEO Custom Fuzz Testing is a commercial penetration testing tool by FYEO. vaf is a free penetration testing tool. Compare features, ratings, integrations, and community reviews side by side to find the best penetration testing fit for your security stack.
CST VerdictBased on our analysis of NIST CSF 2.0 coverage, core features, company size fit, deployment model, here is our conclusion:
Mid-market and enterprise teams securing Layer-1 protocols, smart contracts, or custom DeFi runtimes need FYEO Custom Fuzz Testing because it builds harnesses around your actual threat model instead of running generic fuzzing templates against your code. The stateful execution with shadow-state tracking and invariant checking catches logic flaws that stateless fuzzers miss, and CI integration means you're re-running those same reproducible seeds on every release. Skip this if your codebase is small or you're looking for a self-service tool; FYEO's 12-person team is built for hands-on engagement with mid-market and up, and that model doesn't scale to solo developers or teams that need instant turnaround.
Penetration testers who need to rapidly iterate fuzzing payloads across multiple endpoints will appreciate vaf's speed and cross-platform portability; the lightweight Nim implementation outpaces Python-based fuzzers on CPU-constrained lab environments by 3-5x. With 321 GitHub stars and active maintenance, it's stable enough for repeatable test runs. Skip this if you need a commercial UI, integrated reporting, or support contracts; vaf is a CLI tool for practitioners comfortable reading source code and troubleshooting their own builds.
