Prefactor

#2 in Observability & Evals

Prefactor · 3× · last seen Jul 30, 2026

96

Momentum

Prefactor is an observability and evaluation platform for AI agents in production. It captures every agent run as a structured Trace (model calls, tool usage, decisions) and evaluates it in real-time for quality, drift, and risk using custom-defined Evals (LLM-as-Judge, technical checks, qualitative metrics). Based on these scores, the platform can pause risky runs, route them for human approval, or block them entirely—rather than just displaying problems retroactively in a dashboard. Integration happens via TypeScript and Python SDKs as well as native integrations with popular agent frameworks; a separate Open Source tool called "Prefactor Evals" (Apache 2.0) supplements the offering with deterministic, LLM-free checks.

Sources (3)