Nyx – multi-turn, adaptive, offensive testing harness for AI agents
We built Nyx to solve a problem we kept hitting while building agents: AI agents break in ways traditional software doesn't. Logic bugs, reasoning failures, edge cases that manual testing and static benchmarks never explore. Nyx is an autonomous testing harness that probes your AI agents to find failure modes before users do. It’s used to find logic bugs, instruction following failures, edge cases in agent behavior, and for red-team security testing (jailbreaks, prompt injection, tool hijacking) Technical approach: * Pure blackbox (no special access needed - test like your users interact) *…
In plain words
Nyx is an autonomous testing harness that probes AI agents to identify failure modes before users encounter them. It finds logic bugs, reasoning failures, instruction-following errors, edge cases, and security vulnerabilities like jailbreaks and prompt injection through multi-turn adaptive conversations. The tool works as a pure blackbox—requiring no special system access—and tests across multiple modalities including text, voice, images, and browser interactions. It runs tests in parallel to autonomously discover weaknesses without requiring manually written test cases.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
We built Nyx to solve a problem we kept hitting while building agents: AI agents break in ways traditional software doesn't. Logic bugs, reasoning failures, edge cases that manual testing and static benchmarks never explore. Nyx is an autonomous testing harness that probes your AI agents to find failure modes before users do. It’s used to find logic bugs, instruction following failures, edge cases in agent behavior, and for red-team security testing (jailbreaks, prompt injection, tool hijacking) Technical approach: * Pure blackbox (no special access needed - test like your users interact) * Multi-turn adaptive conversations * Multi-modal testing (voice, text, images, documents, browser interactions) * Massively parallel by default Instead of spending time writing static evals for the key failure modes of your AI agents, point Nyx at any system and it autonomously discovers failure modes that matter. We typically find issues in under 10 minutes that manual audits take hours to surface. This is early work and we know the methodology is still going to evolve. We would love nothing more than feedback from the community as we iterate on this.
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