OpenAI Chat Completions, OpenAI Responses and Anthropic Messages on one base URL, with Bearer or x-api-key auth. Familiar does not mean identical, so check the compatibility matrix for your workflow.
Routing designed around the task
Send muscle/auto. Flex applies compatibility and funding checks, then selects the best qualified route available for each task.
Explicit spend control
A prepaid service balance, per-key and per-account rate limits, and an X-Request-Id on every response for support.