Amazon Web Services (AWS)
From https://aws.amazon.com/: AWS has the services to help you build sophisticated applications with increased flexibility, scalability and reliability.API Gateway + Lambda
I’ve used AWS to build internal API endpoints at Brightcove. We used API Gateway + Lambda to create a form validation service that tied into both our own database of known invalid emails as well as a 3rd party service we used to define the quality of each lead coming in.
Cloudfont + S3
Brightcove.com had an ever-growing list of datasheets to support our marketing campaigns. I used Cloudfront and S3 to create static buckets for these pdfs under a custom subdomain for sharing as part of these campaigns.