New billing system based on actual pound balance instead of credits, as well as support for pre-paid request packs for volume discounts. This introduces new headers:

chimnie-balance-used: Amount deducted from your balance for the request.

chimnie-balance-remaining: Balance remaining after the request.

chimnie-pack-used: Number of pack request units consumed by the request. 

chimnie-pack-kind: The kind (core / plus / premium / commercial) of the pack that satisfied the request. 

chimnie-pack-remaining: Number of requests remaining across all your active packs of that kind, after the request. 

Former credit-based headers will be kept for backwards compatibility for some time.

Full details on the current billing system are available in our documentation https://docs.chimnie.com/#billing-system