Fabraix is a San Francisco company founded by Ahmed Aly and Ibrahim Abdu and backed by Y Combinator's Summer 2026 batch. It builds adversarial AI agents that test other AI agents, positioning continuous offensive testing as the security discipline that static benchmarks and point-in-time audits cannot cover.
Its flagship product Nyx is a pure-blackbox red-teaming agent that takes only an endpoint, URL, or phone number, draws on a library of more than 10,000 adversarial strategies, and reports findings with reproduction steps and AIVSS-scored severity. Fabraix also offers Arx, a run-time defence layer informed by Nyx findings, and publishes ACE, a benchmark measuring the token cost an attacker must spend to breach an agent.
Nyx is Fabraix's autonomous red-teaming agent that probes AI agents for security, logic, and alignment failures through blackbox adversarial campaigns.
