AWS Step Functions makes it easy to coordinate the components of distributed applications as a series of steps in a visual workflow. You can quickly build and run state machines to execute the steps of your application in a reliable and scalable fashion.

Developer Guide
Describes key concepts of AWS Step Functions and provides instructions for using the features of AWS Step Functions.
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Amazon States Language Specification
Describes the language that is used to define state machines for AWS Step Functions.

API Reference
Documents the AWS Step Functions API.

Statelint on Github
A tool to validate your Amazon States Language code.