Postman - The Collaboration Platform for API Development
Apigee - Intelligent and complete API platform
Apiary - Collaborative design, instant API mock, generated documentation, integrated code samples, debugging and automated testing
Django REST framework - Django REST framework is a toolkit for building web APIs.
Koofr - Koofr offers safe EU based cloud storage with free storage space for life and options to connect multiple cloud accounts (Dropbox, Google Drive, OneDrive) and your personal storages.
Amazon API Gateway - Create, publish, maintain, monitor, and secure APIs at any scale