Bring Your Own Key means using a gateway's interface while authenticating with your own provider API keys, so providers bill you directly and the gateway never holds your balance. OpenRouter's BYOK tier is free up to a $25,000 monthly allowance measured at list-price inference cost, then charges a 5% fee on usage above it.
Why it matters
BYOK separates two things gateways usually bundle: the integration convenience and the billing relationship. Teams with negotiated provider rates, compliance requirements on payment flows, or existing credits keep their own billing while gaining the multi-model surface.
The fee math, concretely
The BYOK allowance is measured in list-price inference dollars, not request count, so request volume alone does not determine when the 5% fee starts. Below the allowance BYOK costs nothing beyond list price; a flat-fee control plane ($49/month) beats the 5% overage only past roughly $25,980 of monthly list-price inference. Run your own numbers in the fee calculator.
Common questions
Does BYOK expose my API keys?
The gateway necessarily handles your key to forward requests; whether it stores keys, and how, is a per-vendor security question worth asking directly. Self-hosted gateways keep keys entirely in your infrastructure.
Does BYOK change rate limits?
You keep your own provider rate limits and tier, which is often the point: negotiated enterprise limits survive the gateway.
Is BYOK cheaper than credits?
Under the free monthly threshold, clearly. Above it, roughly a wash against credit fees, and both lose to flat-fee options at higher spend.
Compare any two models
List rates and dated competitor measurements: prices and measured bills. Pareto 26.9 measured task costs are not published. Verbosity: Edition 2.