What Is GraphQL?

Facebook built GraphQL in 2012 to solve a simple problem: their mobile apps were slow because they needed multiple API calls to load a single screen.

GraphQL is just a smarter way to build APIs. Instead of multiple endpoints with fixed responses (REST), you get one endpoint with custom responses.

REST: Multiple trips to get data

await fetch('/users/123')      // Get user
await fetch('/users/123/posts') // Get posts  
await fetch('/users/123/followers') // Get followers
// 3 requests = slow

GraphQL: One trip, exactly what you need

query {
  user(id: 123) {
    name
    posts { title }
    followers { count }
  }
}
// 1 request = fast

The 3 Core Concepts

1. Schema (Your API Menu)

type User {
  id: ID!           # ! means required
  name: String!
  posts: [Post!]!   # [] means list
}

type Post {
  id: ID!
  title: "String!"
  author: User!
}

2. Queries (Getting Data)

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

3. Mutations (Changing Data)

mutation {
  createPost(title: "\"Hello World\") {"
    id
    title
  }
}

That's it. You now understand GraphQL.

Why Use GraphQL?

The Good:

• No over-fetching - Get exactly what you need
• No under-fetching - Get everything in one request
• Self-documenting - Schema tells you what's available
• Multiple clients - Mobile and web can use the same API differently

The Bad:

• Caching is harder - Need tools like Apollo Client
• N+1 queries - One query can trigger 100 database calls
• Learning curve - Your team needs to learn new concepts

When to Use GraphQL vs REST

Use GraphQL When:

• Multiple clients need different data
• You're making 5+ API calls per page
• You have deeply nested data relationships
• You want real-time features

Stick with REST When:

• Your API is simple CRUD
• You need bulletproof HTTP caching
• You're building a public API
• Your team is productive with REST

The Truth

GraphQL isn't better than REST. It solves different problems.

Facebook didn't build it because REST sucks - they built it because they had Facebook-scale problems.

Most apps? REST works fine.

But if you're making 10 API calls per page and your mobile app is slow? Time to look at GraphQL.