GraphQL vs REST: When do I use one or the other?

For more than 10 years, I've been using and programming REST APIs. It's by far one of the simplest systems to integrate when it comes to APIs. It's essentially based on HTTP requests that take the form of well-known methods such as GET, POST, PUT, and DELETE. It's hard to be more efficient in terms of simplicity.

In terms of security, authorization in REST is generally done via the header or with a token system, like OAuth, which is a fairly standardized solution.

Then, in 2015, Facebook introduced GraphQL. But what does "QL" mean? It's short for Query Language. GraphQL allows you to request only the specific information you need. It's an approach I really like, especially because when developing an API, you don't always know exactly how the frontend will manipulate the information.

In REST, an API often uses Swagger for documentation and interaction. Swagger is a specification that describes the available endpoints in an API, the types of possible requests (GET, POST, etc.), and the expected parameters. Swagger also provides a graphical interface that makes it easy to test the different API routes, which is a great advantage for developers.

Both models allow you to specify input parameters. However, in Swagger, it is difficult to specify return parameters. REST, by default, often returns all information at once, even those that are not necessary. GraphQL does not encounter this problem, as the client can specify exactly which fields it wants in the response.

In REST, it may be necessary to make multiple HTTP requests to obtain information from different models. GraphQL, on the other hand, allows you to combine multiple models in a single request. Additionally, GraphQL excels at managing complex relationships between objects, where REST shows its limitations.

Although GraphQL has advantages, its implementation complexity is a disadvantage. It is necessary to use libraries like Graphene in Python and sub-plugins like graphene-django. File upload also remains a difficulty with GraphQL, where you often have to encode files in base64, which makes requests heavier.

In situations where there is a clear separation between backend and frontend developers, I favor GraphQL. It gives a lot of independence to the frontend, which can explore APIs autonomously. On the other hand, REST remains simpler and may be better suited to projects where API needs are more basic.

Ultimately, REST remains an excellent solution for simple and easy-to-maintain projects. However, GraphQL is becoming increasingly essential when working with complex systems where multiple requests and relationships must be managed efficiently. For my recent projects, I mainly use GraphQL, especially when collaboration between frontend and backend is crucial.