Microsoft today announced the public preview release of two new Azure Billing APIs: the Azure Usage API and Azure RateCard API which provide customers and partners programmatic access to their Azure consumption and pricing details. Customers and partners can use the Azure Resource Usage API to get their estimated Azure consumption data. Customers and partners can use the Azure Resource RateCard API to get the list of available Azure resources, along with estimated pricing information for each.
You can also use the new Billing APIs directly to write your own custom reports and billing tracking logic. To get started with the APIs, you can leverage the code samples on Github. The Billing APIs leverage the new Azure Resource Manager and use Azure Active Directory for Authentication and follow the Azure Role-based access control policies.
Read more about it here.