Onyx Platform vs Promptfoo MCP Proxy: Side-by-Side Comparison (2026)

Onyx Platform

Mid-market and enterprise security teams deploying AI agents across multiple LLMs need Onyx Platform because it's the only control plane that catches shadow AI deployments and unapproved model usage before they become compliance violations. The natural language policy engine and real-time prompt injection blocking cover both governance (GV.PO) and continuous monitoring (DE.CM) without requiring security teams to become prompt engineers. Skip this if your organization runs fewer than three LLM integrations or if you need post-incident forensics more than active agent behavior enforcement; the session replay is solid but the tool's real strength is prevention during runtime, not reconstruction after the fact.