AWS AppSync

AWS AppSync is a fully managed serverless service from Amazon Web Services for building GraphQL and Pub/Sub APIs that allow applications to access and update data from multiple sources through a single endpoint. Modern web and mobile applications often need to combine information from databases, microservices and third-party APIs, and fetching data from each source separately increases latency, network usage and client complexity. Building a robust GraphQL server, handling real-time subscriptions and managing offline synchronisation also requires significant engineering effort. AppSync addresses these challenges by providing a managed GraphQL layer that connects to multiple data sources, handles scaling automatically, and supports real-time updates. Its approach allows developers to define a schema and resolvers while AWS manages infrastructure, security and performance, enabling faster development of responsive, data-driven applications without operating servers.

Key features include data source integrations with Amazon DynamoDB, Amazon Aurora, Amazon OpenSearch Service, AWS Lambda and HTTP endpoints, allowing a single query to retrieve data from several sources. Resolvers can be written in JavaScript or Velocity templates, and pipeline resolvers support multi-step logic. Real-time capabilities include GraphQL subscriptions and AppSync Events, which provide serverless WebSocket APIs for broadcasting updates to connected clients. Offline data synchronisation and conflict resolution are supported through AWS Amplify client libraries, and merged APIs allow teams to combine multiple source APIs into one. Security options include API keys, AWS Identity and Access Management, Amazon Cognito user pools, OpenID Connect and Lambda authorisers, with fine-grained access control at field level. Caching, monitoring through Amazon CloudWatch and tracing with AWS X-Ray support performance and troubleshooting. AppSync is used by developers and organisations of all sizes building web, mobile and IoT applications on AWS. Pricing is usage-based and is not published in this listing, and no free trial or free version information is provided here.