REST vs GraphQL: API Architecture Comparison

API design is one of the foundations of every web application. Two giants: REST and GraphQL. Which is right for your project?

What Is REST?

REST (Representational State Transfer) is a resource-based API architecture. Each resource is represented by a URL.

GET    /api/users          -- All users
GET    /api/users/1        -- Single user
POST   /api/users          -- New user
PUT    /api/users/1        -- Update user
DELETE /api/users/1        -- Delete user

What Is GraphQL?

GraphQL is a query language developed by Facebook. It lets you request exactly the data you need from a single endpoint.

query {
  user(id: 1) {
    name
    email
    posts {
      title
    }
  }
}

Detailed Comparison

| Criteria | REST | GraphQL | |----------|------|---------| | Endpoints | Multiple | Single endpoint | | Data fetching | Fixed structures | Client determines | | Over-fetching | Yes | No | | Under-fetching | Yes | No | | Caching | Built-in HTTP cache | Custom caching needed | | File upload | Easy | Complex | | Learning curve | Low | Medium | | Error handling | HTTP status codes | Custom error format | | Real-time | Webhook/polling | Subscriptions | | Documentation | Swagger/OpenAPI | Introspection (automatic) |

Over-fetching and Under-fetching

Over-fetching

In REST, you want just a user's name but get everything:

// GET /api/users/1 -- You only wanted the name
{
  "id": 1,
  "name": "Ali",
  "email": "ali@test.com",
  "address": "...",
  "phone": "...",
  "preferences": "..."
}

In GraphQL, request only what you need:

query {
  user(id: 1) {
    name
  }
}

Under-fetching

In REST, building a page may require multiple requests:

GET /api/users/1
GET /api/users/1/posts
GET /api/users/1/followers

In GraphQL, get all data in one request:

query {
  user(id: 1) {
    name
    posts { title }
    followers { name }
  }
}

When to Choose REST?

• Simple CRUD operations
• HTTP caching matters
• File upload/download heavy
• Team is familiar with REST
• Small-medium scale projects
• Public APIs (third-party integration)

When to Choose GraphQL?

• Complex data relationships
• Mobile + web need different data
• Performance critical (minimal data transfer)
• Fast-changing requirements
• Large, complex applications
• Frontend-driven development

Popular Tools

REST

• Express.js, Fastify
• Swagger/OpenAPI
• Postman

GraphQL

• Apollo Server/Client
• Relay
• GraphQL Playground
• Hasura (automatic GraphQL)

Conclusion

REST and GraphQL aren't replacements — they're complementary technologies. REST is sufficient for simple projects. For modern applications with complex data requirements, GraphQL provides a big advantage. Some projects use both together.

If you'd like to build APIs with REST or GraphQL, get in touch: info@cagribilgehan.com. Check out my projects: cagribilgehan.com