Opper AI Review 2026

European AI gateway and agent control plane — 300+ models behind one OpenAI-compatible SDK with a 3% platform fee, EU hosting, and BYOK.

Opper AI is a Stockholm-based AI gateway and agent control plane positioned as a European alternative to OpenRouter, Portkey, and similar multi-provider routing layers. Through a single SDK that is drop-in compatible with the OpenAI client, you can call 300+ models from 25+ providers (OpenAI, Anthropic, Google, Mistral, Cohere, Meta, Groq, plus open models) and Opper handles routing, fallbacks, retries, caching, and observability. The Gateway tier charges a flat 3% platform fee on top of the underlying model cost. The Control Plane tier (5.5% on calls that use its features) adds Observe (LLM-as-judge auto-scoring), Route (zero-downtime model switching per org/project/function), Steer (Observe-driven prompt and few-shot optimization), Guard (PII masking, content filtering, policy rules), and Comply (model allowlists by provider/region/country, monthly budget caps, retention controls). The differentiator is geography and posture: all inference is routed through EU regions, BYOK is supported on every tier so you can plug in your own provider credits, no customer data is used to train models, and the company is structured for GDPR-aligned procurement. Pay via Stripe with prepaid credit balances and optional auto top-up. Opper is a strong fit when you want one API, one bill, EU data residency, and observability without standing up your own LiteLLM/Langfuse stack.