The [Amazon SDK for JavaScript V3 API Reference Guide](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/) describes in detail all the API operations for the Amazon SDK for JavaScript version 3 (V3). 

# What's different between the Amazon SDK for JavaScript v2 and v3
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 This section captures notable changes from Amazon SDK for JavaScript v2 to v3. Because v3 is a modular rewrite of v2, some basic concepts are different between v2 and v3. You can learn about these changes in our [blog posts](https://aws.amazon.com/blogs/developer/category/developer-tools/aws-sdk-for-javascript-in-node-js/). The following blog posts will get you up to speed: 
+  [Modular packages in Amazon SDK for JavaScript](https://aws.amazon.com/blogs/developer/modular-packages-in-aws-sdk-for-javascript/) 
+  [Introducing Middleware Stack in Modular Amazon SDK for JavaScript](https://aws.amazon.com/blogs/developer/middleware-stack-modular-aws-sdk-js/) 

 The summary of interface changes from Amazon SDK for JavaScript v2 to v3 is given below. The goal is to help you easily find the v3 equivalents of the v2 APIs you are already familiar with. 

**Topics**
+ [Client constructors](migrate-client-constructors.md)
+ [Credential providers](migrate-credential-providers.md)
+ [Amazon S3 considerations](migrate-s3.md)
+ [DynamoDB document client](migrate-dynamodb-doc-client.md)
+ [Waiters and signers](migrate-waiters-signers.md)
+ [Notes on specific service clients](migrate-service-client-notes.md)