GraphQL is an API query language and runtime that lets an application request the exact data it needs. A typed schema defines available data and operations, while the server resolves each request from one or more underlying services or databases.
GraphQL
What is GraphQL?
GraphQL is an API query language and runtime that lets an application request the exact data it needs. A GraphQL API follows a typed schema. It is not a database or frontend framework.
How a GraphQL API works
The schema is the shared contract between an app and its API.
- Define types, fields, and allowed operations in a schema.
- Send a query to read data, or a mutation to change it, with reusable variables.
- Validate the request against the schema.
- Run resolvers that fetch data from services or databases.
- Return JSON shaped like the query. Subscriptions can send selected live updates.
GraphQL vs. REST API
Neither approach is automatically better.
| GraphQL | REST |
|---|---|
| Usually one API endpoint | Usually multiple resource endpoints |
| Client chooses response fields | Server defines response shape |
| Flexible, but caching needs planning | HTTP caching is often simpler |
| Add fields without new versions | Versioned endpoints are common |
Benefits of using GraphQL
It suits connected, changing application data.
- Returns only requested fields.
- Can combine related data in one request.
- Provides a typed, discoverable contract.
- Can unify several backend services.
Practical limits and security concerns
Flexibility needs controls.
- Slow resolvers can create expensive requests.
- Use query depth and cost limits.
- Apply authorization to each field, not only the endpoint.
- Use rate limits and monitor errors.
When to use GraphQL
Choose it for data-rich products, varied web or mobile clients, or one API layer over multiple sources.
- Use REST for simple, stable resource operations.
- Use direct file delivery for large downloads.
GraphQL in application development
Teams define a schema, connect resolvers, test operations, and document expected data. App design and development can include a GraphQL-backed API, and AI app builders such as Emergent can help build, test, and ship the full-stack application around it.
Frequently Asked Questions
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What is GraphQL used for?
GraphQL is used to let web and mobile apps retrieve and update API data in a client-selected shape.
How does GraphQL work?
A server validates a query against its schema, runs resolvers, and returns matching JSON.
Is GraphQL better than REST API?
Not always. GraphQL helps with connected and varied data needs, while REST can be simpler for straightforward APIs and HTTP caching.
How do you use GraphQL?
Send a query, mutation, or subscription to a GraphQL endpoint using its documented schema.
Is GraphQL a framework or a database?
No. It is an API specification and runtime that can sit in front of many databases and services.
When should you use GraphQL?
Use it when multiple clients need flexible access to related data or when one API must aggregate several backend systems.
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