REST or GraphQL: Making the Right API Choice for Your Application

As modern applications continue to evolve, the need for flexible, efficient, and performant APIs has become more critical. REST (Representational State Transfer) has been the go-to standard for building APIs, but with increasing complexity in client requirements, a newer API technology has gained traction: GraphQL.

In this blog, we will dive deep into understanding when to use GraphQL and how it differs from REST. We’ll explore key use cases, differences in architecture, and benefits and trade-offs, helping you make informed decisions about which technology is right for your next project.

What is GraphQL?

GraphQL, developed by Facebook in 2012, is a query language for your API that allows clients to request only the data they need. It offers a more flexible and powerful alternative to REST, enabling the client to define the structure of the response.

In contrast to REST’s fixed endpoints and predefined data formats, GraphQL allows a client to specify exactly what data they want from a single endpoint, making API interactions more efficient.

What is REST?

REST, a well-established architecture style, defines a set of constraints for creating web services. In REST, data is typically accessed through multiple endpoints (URLs), each representing a resource. REST APIs rely on HTTP methods (GET, POST, PUT, DELETE) for communication.

REST APIs generally serve full data objects for each request, even when only a small portion of the data is needed. This can result in over-fetching (retrieving more data than necessary) or under-fetching (requiring multiple API calls to get all the needed data).

Key Differences Between GraphQL and REST

1. Data Fetching

• REST: Each endpoint corresponds to a resource, and the response data is predefined, meaning clients receive all data associated with that resource. For example, retrieving a list of users will return all fields (e.g., name, email, and address) even if the client only needs the user’s name.
• GraphQL: Clients can request only the specific data they need. Instead of multiple API requests, a single GraphQL query can fetch related data across various resources, reducing over-fetching.

Example: In REST, to retrieve a user and their associated posts, you may need two API requests (one for the user and one for posts). In GraphQL, a single query can retrieve both the user and the posts in one go.

2. Endpoints

• REST: REST relies on multiple endpoints for different resources (e.g., /users, /posts, /comments). Each request will hit a different URL.
• GraphQL: GraphQL uses a single endpoint to serve all requests. The client defines what they need through a query structure, which is interpreted by the server to return the appropriate data.

3. Versioning

• REST: As APIs evolve, new versions are often created, leading to versioned endpoints (e.g., /api/v1/users, /api/v2/users). This can result in backward compatibility issues and version management complexities.
• GraphQL: No versioning is required in GraphQL. The schema can evolve over time by adding fields or deprecating older ones, providing a seamless way to update APIs without creating new versions.

4. Over- and Under-fetching

• REST: Over-fetching occurs when a REST API returns more information than the client needs, while under-fetching happens when the client needs additional API requests to get all necessary data. Both of these are common with REST APIs.
• GraphQL: With GraphQL, clients define exactly what data they want to retrieve, so there's no over- or under-fetching. This is particularly beneficial for mobile and web applications where performance and bandwidth are critical.

5. Error Handling

• REST: Error handling in REST is standardized using HTTP status codes (e.g., 404 Not Found, 500 Internal Server Error). These codes provide clarity but are sometimes not sufficient to explain detailed application-specific errors.
• GraphQL: Errors in GraphQL are handled differently. Instead of relying on HTTP status codes, GraphQL returns a data field (even in partial failures) and an errors array with detailed information about any issues encountered during the query execution.

6. Request Complexity

• REST: REST follows the concept of multiple round trips for complex data structures, requiring developers to plan the API endpoints carefully to meet the requirements.
• GraphQL: GraphQL can handle complex queries with relationships between data through nested queries, significantly reducing round trips and simplifying data access for complex apps.

When to Use GraphQL Over REST

While both GraphQL and REST have their use cases, there are specific scenarios where GraphQL can offer distinct advantages.

1. Complex Data Relationships

If your API involves fetching complex and deeply nested data structures with multiple relationships (e.g., user profiles with associated posts, likes, and comments), GraphQL excels at querying all this data efficiently in a single request.

2. Client-Driven Queries

When clients (web, mobile, or IoT devices) have different data needs and you want to give them the flexibility to ask for only the information they require, GraphQL is an excellent choice. It minimizes bandwidth and optimizes performance.

3. Rapid Iteration and Evolving APIs

If you expect your API to evolve frequently and want to avoid breaking changes or maintaining multiple API versions, GraphQL allows for easier schema updates and deprecation of fields without requiring new endpoints.

4. Multiple Data Sources

GraphQL is great for aggregating data from multiple sources (databases, microservices, etc.) in a single query, making it ideal for apps that require data from diverse backends.

When REST is Better Suited

While GraphQL offers several benefits, there are scenarios where REST might still be a better choice:

1. Simple APIs with Minimal Data Complexity

For basic CRUD (Create, Read, Update, Delete) applications, REST’s straightforward design can be simpler and more intuitive to implement.

2. Caching and Performance

REST APIs benefit from HTTP caching mechanisms, which are more challenging to implement in GraphQL due to its dynamic query structure. If caching is critical to your app’s performance, REST may be more efficient.

3. Security

While GraphQL’s flexibility is a strength, it can also be a security risk. Developers must ensure that the API limits query complexity and prevents abusive or overly expensive queries. REST, with predefined endpoints, provides more natural boundaries for securing an API.

Conclusion

GraphQL and REST serve different purposes and have their unique strengths. GraphQL offers unparalleled flexibility and efficiency, especially for applications with complex data needs or multiple client types. On the other hand, REST remains a solid choice for simpler applications and where caching, tooling, and existing infrastructure are better suited to RESTful APIs.

The decision to use GraphQL or REST should be driven by the specific requirements of your application. Understanding the trade-offs between these two technologies will help you build APIs that are not only robust but also efficient and scalable.

Reference

• https://graphql.org
• https://restapitutorial.com
• https://www.apollographql.com
• https://www.howtographql.com/basics/3-big-differences-between-graphql-and-rest
• https://github.blog/2016-09-14-the-github-graphql-api
• https://medium.com/@yourname/graphql-vs-rest-real-difference
• https://towardsdatascience.com