What Is GraphQL?

A GraphQL server exposes a single endpoint (typically /graphql). The client sends a POST request with the query describing what data it wants. The server resolves the query by calling the appropriate data sources and returns JSON matching the query shape.

Resolvers are server-side functions that fetch data for each field in the query. A 'user' resolver might query PostgreSQL, a 'posts' resolver might query MongoDB, and a 'friends' resolver might call another API — all composed into one response.

The GraphQL schema (written in SDL — Schema Definition Language) defines types, fields, and relationships. Tools like Apollo Server and Yoga handle parsing, validation, and execution of queries against the schema.

GraphQL excels for mobile applications where bandwidth is limited. Instead of downloading 10KB of data when you only need 2KB, GraphQL returns exactly what's needed — improving load times and reducing data costs.

For applications with complex data requirements (dashboards, social feeds, nested relationships), GraphQL's ability to fetch related data in one request dramatically simplifies frontend development.

However, GraphQL adds complexity on the server side. For simple CRUD APIs, REST is simpler. GraphQL shines when clients have diverse data needs or when multiple frontend clients (web, mobile, third-party) consume the same API.

JK Tech Hub builds GraphQL APIs when projects require complex data fetching patterns. We use Apollo Server with TypeScript, implementing efficient resolvers, DataLoader for batching, and proper authentication.

We recommend GraphQL for: dashboards with complex data aggregation, mobile apps needing bandwidth optimization, and applications serving multiple client types. For simpler APIs, we recommend REST for its lower complexity.

Our GraphQL implementation includes schema-first design, code generation for type-safe resolvers, playground for development, and caching strategies with Apollo Client on the frontend.