API budget control
How to control AI API costs with budgets and prepaid balance
AI API usage can grow quickly when agents, retries, long context, or multiple teammates share keys. Budget controls let teams cap spend before a request is sent upstream.
Budget controls that matter
Useful controls happen before routing. A gateway should check wallet balance, daily and monthly key budgets, model allowlists, IP rules, and max output limits before sending a request.
Common use cases
Budget controls are most useful for internal tools, SaaS trials, customer-facing agents, and background jobs that can retry or fan out unexpectedly.
- Limit each API key by daily and monthly spend
- Keep high-cost models behind explicit allowlists
- Set smaller max output limits for trial or test keys
Prepaid vs overage billing
Prepaid gateways stop when balance reaches zero. Overage systems may keep serving requests and create an invoice later. For small teams, prepaid balance is easier to reason about.
FAQ
Should failed requests be billed?
Balance and budget rejections should not be billed. Upstream failures before a usable response should not create a deduction.
Can budgets replace logs?
No. Budgets stop spend, while request-level logs explain where the spend went.