The HTTP data source provides a way to send an HTTP request directly from AppSync. This is a versatile approach as most things on the Web offers an HTTP API. It provides a direct way of interacting with things like Google Sheets, OpenWeatherMap, or even sending messages to a Telegram bot, and a lot more. Even individual services in AWS provide HTTP-based APIs, those are what the AWS CLI, the SDK, Terraform, and other tools are using under the hood.