AWS itself is a great example: Most Amazon Web Services (e.g. S3, EC2) can be controlled and accessed via APIs, and Amazon charges for that API access. Here's a

AWS itself is a great example: Most Amazon Web Services (e.g. S3, EC2) can be controlled and accessed via APIs, and Amazon charges for that API access. Here's a more concrete example --- the pricing page for Amazon DynamoDB: https://aws.amazon.com/dynamodb/pricing/ https://aws.amazon.com/dynamodb/pricing/