This document discusses building a scalable cloud API gateway using AWS AppSync. It covers some of the challenges of building custom GraphQL servers like security, scalability, developer velocity, and costs. It then introduces AWS AppSync as a managed GraphQL service and how it addresses these challenges. The steps to define a schema, configure authentication, choose data sources, and write resolver logic in AWS AppSync are outlined. Finally, deployment options for AWS AppSync like AWS Amplify, AWS CDK, and Serverless Framework are mentioned along with a live demo.