For over a decade, REST (Representational State Transfer) has been the undisputed standard for designing web APIs. However, in 2015, Facebook open-sourced GraphQL, offering a radically different approach to data fetching.
Understanding the strengths and weaknesses of REST and GraphQL is critical for designing scalable, maintainable systems.
Core Concepts
REST (Representational State Transfer)
REST is an architectural style based on resources and endpoints. You use standard HTTP methods (GET, POST, PUT, DELETE) to interact with distinct URLs representing entities.
Example REST Requests:
GET /users/123(Fetches user details)GET /users/123/posts(Fetches posts by the user)
GraphQL
GraphQL is a query language for APIs. Instead of multiple endpoints, a GraphQL API typically exposes a single endpoint (e.g., /graphql). Clients send a query describing exactly the data they need, and the server responds with only that data.
Example GraphQL Query:
query {
user(id: "123") {
name
email
posts {
title
}
}
}The Problems GraphQL Solves
1. Over-fetching
In REST, calling GET /users/123 might return 50 fields (name, email, address, preferences, etc.). If your UI only needs the user’s name, you have “over-fetched” 49 unnecessary fields, wasting bandwidth. GraphQL solves this because you explicitly request only the name field.
2. Under-fetching (N+1 Problem)
In REST, if you need a user’s details and their recent posts, you often have to make two requests: one to /users/123 and another to /users/123/posts. GraphQL allows you to fetch the user and their nested posts in a single request.
3. Strong Typing
GraphQL APIs are defined by a strict schema. The schema dictates exactly what queries are allowed and what types (String, Int, Boolean) they return. This enables incredible developer tooling and auto-completion.
The Strengths of REST
Despite GraphQL’s hype, REST remains dominant for several good reasons:
1. HTTP Caching
Because REST uses standard URLs, it integrates perfectly with browser caching, CDNs, and proxy servers. A GET request to /users/123 can be easily cached at the network edge. Caching GraphQL is notoriously difficult because every request usually goes to the same /graphql endpoint via a POST request.
2. Simplicity
REST is conceptually simpler. It relies on standard HTTP status codes (200 OK, 404 Not Found) and standard verbs. GraphQL, however, almost always returns a 200 OK, even if there are errors in the query, requiring you to parse the JSON payload to find the errors array.
3. File Uploads
REST handles file uploads (multipart/form-data) natively and simply. While file uploads are possible in GraphQL, they require complex workarounds or third-party specifications.
When to Use Which?
Choose GraphQL when:
- You are building a complex UI that requires data from many different related entities.
- You have multiple clients (web, iOS, Android) that require vastly different shapes of data.
- You want to optimize for minimal network payloads (crucial for slow mobile networks).
Choose REST when:
- You are building a simple, resource-based CRUD application.
- Caching at the HTTP/CDN level is a critical performance requirement.
- You are exposing a public API for third-party developers (REST is more universally understood).
Conclusion
GraphQL is not a replacement for REST; it is an alternative tool designed for highly interconnected data and complex client applications. For straightforward, cacheable, resource-based systems, REST remains the gold standard.