PromptUnit is an AI inference proxy that uses AI-powered request classification, quality benchmarking, prompt compression, token-inflation defense, and multi‑model routing to automatically send each call to the cheapest model that meets your quality bar, giving per-call cost and usage visibility, preventing billing attacks, and claiming 40–70% typical savings with a zero-risk 14‑day observation period and a pay-only-on-savings pricing model (20% of verified savings).