A REST API (Representational State Transfer) and GraphQL are two ways to request and manage data from a server, but they work in different ways.

REST API

A REST API organizes data into endpoints. Each endpoint corresponds to a specific type of data and performs a particular action (like getting or creating data). Each endpoint is like a URL you can call to get specific information.

Example:

Let’s say we have an application that shows users and posts.

1. Getting all users: You would call an endpoint like /users. This might return a list of all users.

2. Getting a specific user: To get a specific user by their ID, you’d call /users/1, where 1 is the user ID.

3. Getting posts by a specific user: You’d call /users/1/posts, which would return posts made by that particular user.

REST Limitation: You may get a lot of unnecessary data in each call (called over-fetching), or you may need multiple calls to get everything you need (called under-fetching).

GraphQL

With GraphQL, you have one endpoint, and you specify in the request exactly what data you want, down to the specific fields. This gives you flexibility to request only the data you need, all in a single request.

Example:

Let’s say we have the same application with users and posts.

1. Getting a specific user’s data (with only name and age): You would send a query that specifies exactly that:

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

1. Getting a user with their posts: In one query, you can ask for both the user’s information and their posts:

{
user(id: 1) {
name
posts {
title
content
}
}
}

GraphQL Advantage: With GraphQL, you get only the data you ask for (solving over-fetching) and you can combine multiple requests into one (solving under-fetching).

Summary

REST: Organizes data into separate endpoints. You might need multiple calls to get all the data you want.

GraphQL: Uses one endpoint. You can specify exactly what data you want, all in one call.

Use REST when:

You need simple, predictable data fetching.

Caching is important.

You want an easier setup with widely adopted standards.

Use GraphQL when:

You need flexibility to request specific data fields.

Different clients require different data.

You want to avoid multiple API calls for complex or nested data.

In short:

REST: Good for fixed data and simple operations.

GraphQL: Great for flexible, complex data needs with fewer network requests.