REST vs GraphQL: Which API to Choose? Analysis & Use Cases

You are facing a strategic decision in API architecture and wondering what to choose: the proven REST or the flexible GraphQL? This choice will determine your application's performance, developer velocity, and the future scalability of your system. In this article, we will guide you through an in-depth comparison, showing when it's worth betting on a GraphQL API and when REST remains the better solution. Discover which technology will best meet your business needs and help you avoid costly problems like over-fetching.

Table of contents

Introduction

REST API: A proven standard in API design

• Maturity and ecosystem: A vast amount of documentation, tools, libraries, and experienced developers.


• Simplicity for simple cases: The concept of resources and CRUD operations is intuitive and easy to implement for uncomplicated data models.


• Use of HTTP mechanisms: Native support for caching through HTTP headers, which can significantly improve performance for frequently requested, static resources.

GraphQL API: An alternative approach to server communication

1. Precise data fetching: The client decides the shape of the response, eliminating the problems of over-fetching and under-fetching. It requests specific fields from specific objects, even nested ones.


2. Strongly typed schema: The heart of every GraphQL API is its schema, defined using the Schema Definition Language (SDL). The schema describes all available data types, queries (read operations), mutations (write operations), and subscriptions (real-time communication). It acts as a contract between the client and the server and allows for query validation before execution.


3. Introspection: The schema is "self-documenting". Clients can send a special (introspection) query to find out what operations and data types are available in the API. This drives the development of powerful developer tools like GraphiQL or Apollo Studio.

REST vs GraphQL: Key architectural differences

Data Fetching: The Problem of Over-fetching and Under-fetching

This is the most important difference and the main reason for GraphQL's creation.

• REST: A resource-oriented architecture. The GET /api/posts/1 endpoint returns the entire post object, as defined on the server side. If the frontend only needs the title, the rest of the data (content, creation date, author ID, etc.) is fetched unnecessarily, wasting bandwidth (over-fetching). If we also need the author's name, we have to make a second request to GET /api/users/{authorId} (under-fetching).


• GraphQL: A client-oriented architecture. The client sends a query declaring its needs. To fetch a post's title and its author's name, a single query is sufficient:

    query {
      post(id: "1") {
        title
        author {
          name
        }
      }
    }

The server's response will contain only these two fields. This precision is invaluable in environments with limited bandwidth, such as mobile networks.

Read our comprehensive business guide and learn how to choose the right technology for your app to optimally achieve your goals and avoid blowing your budget:
How to Choose App Technology? A Business Guide

Structure and Endpoints

• **REST:** Utilizes multiple endpoints, each corresponding to a specific resource and a collection of resources (e.g., `/users`, `/users/123`, `/users/123/orders`). As application complexity grows, it leads to a proliferation of endpoints, which can be difficult to manage and version.
• **GraphQL:** Typically operates on a single endpoint (e.g., `/graphql`). All communication happens by sending different queries and mutations to the same address. This simplifies management on both the client and server sides, and API evolution occurs by adding new fields and types to the schema, not by creating new endpoints (which eliminates the need for API versioning like `/v1`, `/v2`).

Schema and Typing: Flexibility vs. Rigor

• **REST:** Has no built-in, standardized mechanism for describing the API. The contract between the client and server is often defined in external documentation, e.g., in the OpenAPI (formerly Swagger) format. This documentation can become outdated, leading to misunderstandings and integration errors.
• **GraphQL:** Requires a strongly typed schema (Schema Definition Language - SDL). The schema is the single source of truth about the API's capabilities. It guarantees that the client will not request a non-existent field and that the server will always return data in the expected format. This strict contract facilitates collaboration between teams and enables the automatic generation of documentation and client-side code.

REST vs GraphQL: Performance and caching

When to use GraphQL instead of REST? Scenario analysis

Advantages and disadvantages of GraphQL in business practice

Advantages (from a business perspective):

• Faster time-to-market for new features: Frontend teams can independently develop the UI, fetching exactly the data they need, without being blocked and waiting for changes in the backend.


• Better user experience (UX) in mobile applications: Faster loading times and lower data consumption directly translate to higher user satisfaction and retention.


• Unified data access in a microservices architecture: GraphQL can act as an API Gateway, aggregating data from multiple distributed services and presenting it to clients as a single, coherent data graph.

• Higher barrier to entry: The team needs to learn new concepts (schemas, queries, mutations, resolvers). Implementing the first GraphQL API can take more time than with REST.


• Server-side complexity: Implementing efficient and secure resolvers, handling field-level authorization, and preventing abuse requires more knowledge and diligence.


• Less mature ecosystem: Although it is developing dynamically, the ecosystem of tools (e.g., for monitoring, rate-limiting) for GraphQL is still not as extensive as for REST.

Example scenarios for GraphQL

GraphQL shines brightest in the following cases:

1. Applications with multiple clients: When the same backend needs to serve a variety of clients (e.g., a desktop web app, a mobile app for iOS and Android, a smartwatch), each with different data requirements.


2. Complex interfaces and dashboards: Applications that need to display data from many different sources on a single screen (e.g., a user profile, a list of their friends, recent activities, and notifications).


3. Microservices-based architecture: GraphQL is an ideal candidate for a facade layer that hides the complexity of communication between multiple internal services from the clients.
   
   Check out our comparison and decide whether a monolith or microservices will work for you before you start rebuilding your API:
   Monolith vs Microservices: Which Architecture to Choose?
   

When REST remains a better choice

REST is still an excellent and often preferred choice for:

1. Simple, resource-centric applications: Systems performing basic CRUD operations on well-defined, loosely coupled resources.


2. Public, open-access APIs: The simplicity and ubiquity of REST make it easy for external developers to integrate. HTTP caching mechanisms are crucial for the performance and scalability of such services.


3. Projects with limited resources: When the team has extensive experience with REST and the implementation time is critical, sticking with a proven technology may be the most sensible business decision.

Migrating from REST to GraphQL: Strategy and best practices

1. Identification and analysis: Identify key use cases where GraphQL will bring the greatest benefits (e.g., the most complex screens in a mobile application).


2. Building the GraphQL schema: Design a GraphQL schema that models the business data in an ideal way for clients, regardless of how it is currently structured in the REST endpoints.


3. Implementing resolvers as wrappers: Write resolvers for the GraphQL schema in a way that they internally query the existing REST endpoints to fetch data. At this point, GraphQL acts as an intelligent intermediary layer that aggregates and transforms data from the REST backend.


4. Gradual client migration: Start switching parts of the client applications (e.g., individual views) from directly querying REST to using the new GraphQL API.


5. Direct database integration: Over time, you can gradually rewrite the resolvers so that instead of querying the old REST endpoints, they communicate directly with databases or other services. This allows for further optimization and the eventual decommissioning of old REST endpoints that are no longer in use.

GraphQL queries: Practical examples

1. Fetch post data: GET /posts/1
   * Server response (over-fetching – we get fields we don't need, like userId or createdAt):

           {
             "id": "1",
             "title": "Introduction to GraphQL",
             "body": "GraphQL is a query language...",
             "createdAt": "2023-10-27T10:00:00Z",
             "userId": "101"
           }
   



2. Fetch author data using the userId from the previous response: GET /users/101
   * Server response (more over-fetching – we get the email, which we don't want):

           {
             "id": "101",
             "firstName": "John",
             "lastName": "Doe",
             "email": "john.doe@example.com"
           }
   

1. Send a GraphQL query to the /graphql endpoint:

       query GetPostWithAuthor {
         post(id: "1") {
           title
           body
           author {
             firstName
             lastName
           }
         }
       }
   

   * The server's response is an exact reflection of the query - no unnecessary data, no additional requests:

           {
             "data": {
               "post": {
                 "title": "Introduction to GraphQL",
                 "body": "GraphQL is a query language...",
                 "author": {
                   "firstName": "John",
                   "lastName": "Doe"
                 }
               }
             }
           }
   

Summary

We understand the doubts related to choosing an API architecture and will gladly help analyze which technology will best support your business goals.

Please fill out the form to discuss your project with our expert.