GraphQL vs REST: Which API Style to Choose

Introduction

Choosing between GraphQL and REST for API development requires understanding their architectural differences, performance characteristics, and developer experience. Both approaches solve different problems, and the optimal choice depends on your application's requirements.

Architectural Differences

REST: Resource-Oriented Design

REST (Representational State Transfer) follows these principles:

1. Resources identified by URIs (/users, /posts)
2. Standard HTTP methods (GET, POST, PUT, DELETE)
3. Stateless communication
4. Cacheable responses

GET /api/users/123 HTTP/1.1
Host: example.com
Accept: application/json

GraphQL: Query Language Approach

GraphQL provides:

1. Single endpoint for all operations
2. Client-defined response structure
3. Strongly typed schema
4. Real-time capabilities via subscriptions

query {
  user(id: 123) {
    name
    email
    posts(limit: 5) {
      title
      createdAt
    }
  }
}

Implementation Comparison

Data Fetching

REST Multiple Endpoints:

GET /users/123
GET /users/123/posts
GET /users/123/followers

GraphQL Single Request:

query {
  user(id: 123) {
    name
    posts {
      title
    }
    followers {
      name
    }
  }
}

Error Handling

REST HTTP Status Codes:

HTTP/1.1 404 Not Found
Content-Type: application/json

{
  "error": "User not found"
}

GraphQL Partial Responses:

{
  "data": null,
  "errors": [
    {
      "message": "User not found",
      "path": ["user"],
      "locations": [{"line": 2, "column": 3}]
    }
  ]
}

Versioning

REST:

GET /v2/users/123

GraphQL (Schema Evolution):

# Deprecate fields instead of versioning
type User {
  name: String!
  email: String! @deprecated(reason: "Use contactEmail instead")
  contactEmail: String!
}

Performance Considerations

Over-fetching vs Under-fetching

REST often suffers from:

• Over-fetching (getting unnecessary data)
• Under-fetching (requiring multiple requests)

GraphQL solves this by letting clients specify exact data requirements.

Network Efficiency

REST (Multiple Requests):

sequenceDiagram
    Client->>Server: GET /users/123
    Server->>Client: User data
    Client->>Server: GET /users/123/posts
    Server->>Client: Posts data

GraphQL (Single Request):

sequenceDiagram
    Client->>Server: POST /graphql (Query)
    Server->>Client: Combined response

Caching

REST benefits from:

• HTTP caching (CDNs, browser cache)
• Simple cache invalidation (on URI changes)

GraphQL requires:

• Persistent queries
• Client-side caching (Apollo, Relay)
• Specialized CDN configurations

Developer Experience

Tooling and Ecosystem

REST:

• Swagger/OpenAPI for documentation
• Postman for testing
• Wide server/client support

GraphQL:

• Built-in introspection
• GraphiQL/Playground IDEs
• Strong typing with schema validation

Frontend Integration

React with REST:

useEffect(() => {
  fetch('/api/users/123')
    .then(res => res.json())
    .then(data => setUser(data));
}, []);

React with GraphQL (Apollo):

const { loading, error, data } = useQuery(gql`
  query GetUser($id: ID!) {
    user(id: $id) {
      name
      email
    }
  }
`, { variables: { id: 123 } });

Schema and Type Systems

REST (OpenAPI Example)

paths:
  /users/{id}:
    get:
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: integer
      responses:
        200:
          description: A user object
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/User'
components:
  schemas:
    User:
      type: object
      properties:
        id:
          type: integer
        name:
          type: string

GraphQL Schema Definition

type User {
  id: ID!
  name: String!
  email: String!
  posts: [Post!]!
}

type Post {
  id: ID!
  title: String!
  content: String!
}

type Query {
  user(id: ID!): User
}

Real-Time Capabilities

REST (Polling):

setInterval(() => {
  fetch('/api/notifications')
    .then(/* handle response */)
}, 5000);

GraphQL Subscriptions:

subscription {
  newNotification {
    id
    message
    createdAt
  }
}

Security Considerations

REST Security

• Standard HTTP security (CORS, HTTPS)
• Rate limiting per endpoint
• OAuth2/JWT authentication

GraphQL Security

• Query depth limiting
• Cost analysis (prevent expensive queries)
• Persisted queries (whitelist operations)

// Apollo Server security example
const server = new ApolloServer({
  typeDefs,
  resolvers,
  validationRules: [
    depthLimit(5),
    createComplexityLimitRule(1000)
  ]
});

Migration Strategies

REST to GraphQL

1. BFF Pattern: Create GraphQL facade over REST APIs

# Resolver implementation
const resolvers = {
  Query: {
    user: async (_, { id }) => {
      const response = await fetch(`https://legacy-api/users/${id}`);
      return response.json();
    }
  }
};

2. Incremental Adoption: Expose GraphQL alongside REST

3. Schema Stitching: Combine multiple GraphQL APIs

When to Choose Each

Choose REST When:

• You need simple, cacheable APIs
• Your clients consume entire resources
• You require standard HTTP caching
• Your team has existing REST expertise

Choose GraphQL When:

• Clients need flexible data requirements

• You have complex, nested data relationships

• Multiple clients consume the same API differently

• You need real-time updates via subscriptions

• Consider API Gateway solutions that support both paradigms