What is Bring your own key?

Bring your own key means a gateway or proxy holds no provider credentials of its own and instead uses API keys you create in your model provider account. Billing then runs through your provider relationship, and access to a model depends on the account attached to that key. Of the tools covered here, Apache APISIX AI Gateway, Arize AI and Braintrust support bring your own key, while 4everland and Aptible do not. The distinction matters for teams that need a single audit trail for model spend, or that must keep keys inside one secret store.