In recent years, there has been a shift in how APIs are designed and developed. While REST APIs have been the standard for many years, a new API query language called GraphQL is gaining popularity as an alternative. In this article, we will examine the differences between REST and GraphQL and the benefits that GraphQL provides over traditional REST.
What is REST?
REST (Representational State Transfer) is an architectural style for building APIs that relies on standard HTTP methods like GET, POST, PUT, and DELETE to fetch or modify resources. With REST APIs, each endpoint represents a resource that can be manipulated via these HTTP methods.
For example, if we had a REST API for a blog platform, some endpoints might include:
- GET /posts – get a list of all posts
- GET /posts/1 – get post with ID 1
- POST /posts – create a new post
- PUT /posts/1 – update post with ID 1
- DELETE /posts/1 – delete post with ID 1
REST uses URLs and HTTP methods to expose resources in a straightforward way. It’s a simple yet flexible architecture that has been widely adopted.
What is GraphQL?
GraphQL is a query language spec that was developed internally by Facebook before being publicly released in 2015. It provides an alternative to REST for building APIs and allows clients to define precisely the data they need in a request.
With GraphQL, there is only a single endpoint that accepts queries. The structure of the data is defined in a schema, which acts as a contract between the client and server. The client can then query the schema for specific fields in an object without having to construct multiple REST requests.
For example, if building the same blog platform API with GraphQL, we could have a single endpoint:
- POST /graphql – accept GraphQL queries
And the client could send a query like:
query {
posts {
id
title
content
}
}
To fetch just the id, title and content for all posts. The response would match the shape of the request and avoid over or under fetching data.
Key Differences Between REST and GraphQL
Now that we have a high-level overview of REST and GraphQL, let’s dive into some of the key differences between the two:
Fixed vs Flexible Endpoints
One major difference is that REST APIs have fixed endpoints while GraphQL has a single flexible endpoint. With REST, each endpoint represents a resource that is manipulated via the request method. Endpoints are usually grouped by resource type (e.g. /users, /posts) and take a set structure.
GraphQL only has one endpoint that accepts queries in the body of the request. The endpoint is flexible because the client can specify exactly what data it needs. Resources are not isolated into siloed endpoints.
Multiple Requests vs One Request
Because REST endpoints represent specific resources, it often requires multiple requests to fetch related data. For example, to retrieve a blog post and related comments, separate requests would be needed:
- GET /posts/1 – get post
- GET /posts/1/comments – get comments for post
With GraphQL, related data can be queried in a single request since you can specify fields on connections:
query {
post(id: 1) {
title
content
comments {
id
content
}
}
}
This allows for fewer round trips between client and server.
Overfetching vs Precise Data
REST endpoints return fixed data structures, which often means you get back more data than you actually need. This overfetching can increase response payloads and load on the API server. With GraphQL, the client specifies exactly what fields it needs so you only get back the data you request.
For example, if retrieving a user profile with REST, the endpoint may return a large JSON response with dozens of fields when all you may need is a name and email.
With GraphQL, the query could specify just the name and email fields to avoid overfetching and reduce bandwidth usage.
Versioning
Versioning REST APIs is often done by including the version number in the URL (e.g. v1/users). When a new version is released, both need to be maintained or old clients will break.
With GraphQL, there is just a single endpoint so versioning via URLs isn’t an option. Instead, the GraphQL schema provides a contract between client and server that acts as the version. The schema can be evolved over time without breaking existing clients.
Benefits of GraphQL
Now that we’ve explored some key differences, let’s look at 3 main benefits of GraphQL compared to REST:
1. Avoid Over and Underfetching
As mentioned above, REST APIs commonly suffer from overfetching and underfetching data:
- Overfetching – endpoints return more data than needed
- Underfetching – multiple round trips required to get all the data you need
GraphQL enables the client to precisely specify only the data it needs. So you don’t get back superfluous data but also avoid unnecessary extra requests.
2. Versioning Built-in
With REST, new API versions can break backwards compatibility and force clients to update. GraphQL schemas define a contract between client and server that act as the version. The schema can be evolved over time without breaking existing clients.
Changes to types and fields can be deprecated first and then removed later while maintaining backwards compatibility during the transition.
3. Developer Experience
GraphQL creates a better developer experience compared to REST. The strongly typed schema serves as documentation for the API so it’s easy to explore and understand what data is available. GraphiQL provides an interactive environment to query the schema and test out requests.
The specificity of queries and responses make it simple to debug requests and handle errors. And libraries like Apollo provide helpful tools for caching, pagination, subscriptions and more.
When is GraphQL a Good Fit?
However, it’s worth noting GraphQL may not be the best choice in all situations. Here are some instances where GraphQL makes sense:
- You need to query multiple related resources in a single request
- Clients need to dynamically access different pieces of data
- You want to decouple frontends and backends (frontend can evolve separately)
- You have public API consumers that will query data in complex ways
- Bandwidth efficiency is important (less overfetching)
REST may be a better choice when:
- You need simple CRUD functionality
- You mostly consume entire resources (not querying specific fields)
- You want low maintenance and simpler implementation
Should You Use GraphQL or REST?
So should you use GraphQL or REST for your next project? Here are a few key questions to consider:
- How complex are your data queries and relationships?
- How often do you need to optimize for bandwidth usage and performance?
- How frequently does your API data schema need to change?
- Do you need internal or external API consumers to have flexibility?
For complex and dynamic data querying needs, GraphQL provides clear benefits. For simple use cases like basic CRUD, REST may be simpler to implement and maintain.
In many cases, a hybrid approach is emerging where REST handles simpler endpoints and workflows while GraphQL handles more complex data queries.
Conclusion
GraphQL provides an alternative to REST that offers flexibility, precision, and performance. By allowing clients to specify exactly what data they need in queries, GraphQL solves many REST pain points like over and underfetching. Its strongly typed schema and interactive environment also create a better developer experience.
However, REST is still better suited for basic CRUD use cases where simplicity and low maintenance is preferable. As API needs grow in complexity, GraphQL becomes a more compelling choice to overcome REST limitations.
Moving forward, we’re likely to see more hybrid API architectures leveraging both REST and GraphQL where each is used for what it does best. GraphQL fills an important niche that REST struggles with – querying relationships and specific fields in connected data.
By leveraging the strengths of both REST and GraphQL, developers can build robust and scalable APIs that provide great performance for clients and optimize bandwidth efficiency.