Getting started

Rate limits

Each key may send 60 requests a minute. Every answer says how many are left.

Headers

Header	Meaning
`X-RateLimit-Limit`	Requests allowed a minute: 60.
`X-RateLimit-Remaining`	Requests left in the current minute.
`Retry-After`	On a `429` only: seconds to wait before the next request.

HTTP/1.1 429 Too Many Requests
X-RateLimit-Limit: 60
X-RateLimit-Remaining: 0
Retry-After: 37

{
    "error": {
        "code": "rate_limited",
        "message": "Too many requests: at most 60 a minute per key."
    }
}

Staying under it

Use webhooks instead of asking for a payment's status in a loop.
Read lists with per_page=100 rather than many small pages.
On a 429, wait for Retry-After before trying again.