Guide
How credits work
What you are charged for, what is free, and what gets refunded.
Credits are prepaid and spent per successful call. Each endpoint has its own price based on the work it actually does, published with its reasoning on the endpoint page and in the price list.
The charging rules
| Situation | Charged? |
|---|---|
| The call succeeds | Yes - the endpoint's listed price. |
| Your arguments fail validation | No. The call never runs, so it is free. |
| The endpoint is disabled or unknown | No. |
| You have too few credits | No. You get 402 and nothing is deducted. |
| A host you targeted is down or unreachable | Yes. We did the work of trying on your behalf. |
| We time out or fail internally | No. Automatically refunded to your balance. |
Why prices differ per endpoint
A flat rate sounds simpler but means light callers subsidise heavy ones. A DNS lookup is one cached query; a broken-link check fetches a page and then up to thirty more URLs. Charging both the same would either overprice the cheap call or lose money on the expensive one, so each is priced by what it consumes.
Tracking your spend
Every response carries two headers, so you can monitor spend without polling a billing endpoint:
http
X-Credits-Charged: 10
X-Credits-Remaining: 1240