# JavaScript resolver tutorials for Amazon AppSync
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Data sources and resolvers are used by Amazon AppSync to translate GraphQL requests and fetch information from your Amazon resources. Amazon AppSync supports automatic provisioning and connections with certain data source types. Amazon AppSync also supports Amazon Lambda, Amazon DynamoDB, relational databases (Amazon Aurora Serverless), Amazon OpenSearch Service, and HTTP endpoints as data sources. You can use a GraphQL API with your existing Amazon resources or build data sources and resolvers from scratch. The following sections are meant to elucidate some of the more common GraphQL use cases in the form of tutorials.

**Topics**
+ [Creating a simple post application using DynamoDB JavaScript resolvers](tutorial-dynamodb-resolvers-js.md)
+ [Using Amazon Lambda resolvers](tutorial-lambda-resolvers-js.md)
+ [Using local resolvers](tutorial-local-resolvers-js.md)
+ [Combining GraphQL resolvers](tutorial-combining-graphql-resolvers-js.md)
+ [Using OpenSearch Service resolvers](tutorial-elasticsearch-resolvers-js.md)
+ [Performing DynamoDB transactions](tutorial-dynamodb-transact-js.md)
+ [Using DynamoDB batch operations](tutorial-dynamodb-batch-js.md)
+ [Using HTTP resolvers](tutorial-http-resolvers-js.md)
+ [Using Aurora PostgreSQL with Data API](aurora-serverless-tutorial-js.md)