Are there rate limits or daily caps?

There are no free-tier daily caps and no tiers to unlock. Usage is limited by your balance: when it reaches zero, requests return 402 insufficient_balance until you add credits. There is no per-minute or per-day request or token meter. We may throttle traffic that is abusive or that endangers the service for other users; if you plan sustained high concurrency, tell us first so capacity is there.