AWS AppSync
- What it is
- Fully managed GraphQL (and Pub/Sub) API service.
- One endpoint; the client asks for exactly the fields it needs, from multiple data sources, in a single request.
- Key capabilities
- Resolvers connect one schema to many back ends: Amazon DynamoDB, Amazon Aurora, AWS Lambda, Amazon OpenSearch Service, HTTP endpoints.
- Real-time subscriptions over WebSockets for live data.
- Offline sync for mobile clients that reconnect later.
- Authorization via Amazon Cognito, IAM, OIDC, or API keys.
- Not to be confused with
- Amazon API Gateway — REST/HTTP/WebSocket APIs where each endpoint returns a fixed shape. AppSync is GraphQL: one endpoint, client-defined response shape, built-in real-time.
- Exam signal
- “GraphQL”, “mobile app with offline sync”, “real-time subscriptions” → AppSync.