APIs that are modern, RESTful, and rich with Usability could make all the difference in onboarding new clients to your business. This session covers usability best practices in exposing basic and complex business functions via simple APIs. In-depth details on building RESTful interfaces, HATEOAS links for navigation and usability, ODATA for standard data retrieval (paging, sorting, selecting, filtering etc), and error handling are covered in this talk. Code samples, and sample API endpoints with request/response data will be shared with the audience. Session will cover using Lambda functions in HTTP(S) URLs, to perform operations on aggregated and single entities.