GraphQL and REST are both popular API design approaches. Here’s when to use each.

REST API Overview

REST (Representational State Transfer) uses HTTP methods to interact with resources.

Characteristics

  • Resource-based: URLs represent resources
  • HTTP methods: GET, POST, PUT, DELETE
  • Stateless: Each request is independent
  • Multiple endpoints: Different URLs for different resources

Example

GET    /api/users
GET    /api/users/123
POST   /api/users
PUT    /api/users/123
DELETE /api/users/123

GraphQL Overview

GraphQL is a query language and runtime for APIs.

Characteristics

  • Single endpoint: One endpoint for all operations
  • Client-driven: Clients specify what data they need
  • Strongly typed: Schema defines all types
  • Flexible queries: Get exactly what you need

Example

# Query
query {
  user(id: "123") {
    name
    email
    posts {
      title
      content
    }
  }
}

# Mutation
mutation {
  createUser(name: "John", email: "[email protected]") {
    id
    name
  }
}

Key Differences

1. Data Fetching

REST:

# Multiple requests
GET /api/users/123
GET /api/users/123/posts
GET /api/users/123/followers

GraphQL:

# Single request
query {
  user(id: "123") {
    name
    posts { title }
    followers { name }
  }
}

2. Over-fetching and Under-fetching

REST:

  • Over-fetching: Get more data than needed
  • Under-fetching: Need multiple requests

GraphQL:

  • No over-fetching: Get exactly what you need
  • No under-fetching: Get all data in one request

3. Versioning

REST:

GET /api/v1/users
GET /api/v2/users

GraphQL:

# Add new fields without breaking
type User {
  id: ID!
  name: String!
  email: String!
  phone: String  # New field, optional
}

When to Use REST

Use REST When:

  1. Simple CRUD operations

    • Standard create, read, update, delete
    • No complex relationships

  2. Caching is important

    • HTTP caching works well
    • CDN integration

  3. File uploads

    • REST handles file uploads easily
    • GraphQL is more complex

  4. Simple data requirements

    • Fixed data structure
    • No need for flexible queries

  5. Team familiarity

    • Team knows REST well
    • Existing REST infrastructure

REST Example

// Express.js REST API
app.get('/api/users/:id', async (req, res) => {
  const user = await db.getUser(req.params.id);
  res.json(user);
});

app.post('/api/users', async (req, res) => {
  const user = await db.createUser(req.body);
  res.status(201).json(user);
});

When to Use GraphQL

Use GraphQL When:

  1. Complex data relationships

    • Multiple related resources
    • Nested data structures

  2. Mobile applications

    • Reduce over-fetching
    • Save bandwidth

  3. Rapid frontend development

    • Frontend changes don’t require backend changes
    • Flexible queries

  4. Multiple clients

    • Web, mobile, desktop apps
    • Different data requirements

  5. Real-time updates

    • Subscriptions for live data
    • WebSocket support

GraphQL Example

// Apollo Server
const typeDefs = gql`
  type User {
    id: ID!
    name: String!
    email: String!
    posts: [Post!]!
  }
  
  type Query {
    user(id: ID!): User
    users: [User!]!
  }
  
  type Mutation {
    createUser(name: String!, email: String!): User!
  }
`;

const resolvers = {
  Query: {
    user: (_, { id }) => db.getUser(id),
    users: () => db.getUsers(),
  },
  Mutation: {
    createUser: (_, { name, email }) => db.createUser({ name, email }),
  },
};

Hybrid Approach

You can use both:

// REST for simple operations
GET /api/users
POST /api/users

// GraphQL for complex queries
POST /graphql
{
  query: {
    user(id: "123") {
      name
      posts { title }
    }
  }
}

Performance Considerations

REST

  • Caching: HTTP caching works well
  • CDN: Easy to cache at edge
  • Simple: Less overhead

GraphQL

  • Query complexity: Can be expensive
  • N+1 problem: Need data loaders
  • Caching: More complex to implement

Tools and Libraries

REST

  • Express.js: Node.js framework
  • Django REST: Python framework
  • Spring Boot: Java framework
  • FastAPI: Python framework

GraphQL

  • Apollo Server: Node.js GraphQL server
  • GraphQL.js: Reference implementation
  • Graphene: Python GraphQL library
  • Sangria: Scala GraphQL library

Migration Strategy

From REST to GraphQL

  1. Start with queries: Add GraphQL for read operations
  2. Keep REST for writes: Gradually migrate mutations
  3. Coexist: Run both in parallel
  4. Deprecate REST: Once GraphQL is stable

Conclusion

Choose REST if:

  • Simple CRUD operations
  • Caching is critical
  • Team is familiar with REST
  • Standard HTTP patterns work

Choose GraphQL if:

  • Complex data relationships
  • Multiple clients with different needs
  • Mobile-first approach
  • Rapid frontend iteration

You can also use both:

  • REST for simple operations
  • GraphQL for complex queries
  • Best of both worlds

Remember: The best API is the one that:

  • Serves your use case
  • Your team can maintain
  • Performs well
  • Scales with your needs

Don’t choose based on trends—choose based on requirements! 🎯