Now it's time to look at the big question — when is it better to use REST and when GraphQL, especially in the context of microservice architecture.
Approaches to API structure
REST and GraphQL represent two completely different approaches to building APIs.
REST (Representational State Transfer) is based on the resource-oriented concept. Everything in REST is a resource identified by a URI. Example REST routes might look like:
GET /users/123— get user data with ID 123.POST /users— create a user.PUT /users/123— update user data.
Each CRUD operation is tied to HTTP methods: GET, POST, PUT, DELETE.
GraphQL is fundamentally different: it's not resource-oriented, it's a query language. Here you don't have routes, you have a single entry point (usually /graphql) where you send queries describing which data you want.
Example query:
query {
user(id: 123) {
name
email
address {
street
city
}
}
}
GraphQL lets you pick exactly which fields to return, minimizing data redundancy.
Comparison of key characteristics
1. Request handling
In REST each request is tightly coupled to a fixed data structure. For example, an API might return all user data even if you only need name and email.
In GraphQL you build the query yourself and choose which fields you need:
- REST can return "extra" data (over-fetching).
- GraphQL returns exactly what you asked for.
Example of over-fetching:
// REST response (GET /users/123)
{
"id": 123,
"name": "Ivan",
"email": "ivan@example.com",
"phone": "123-456-7890",
"address": {
"street": "Lenina 10",
"city": "Moscow"
}
}
// GraphQL response for query { user(id: 123) { name email } }
{
"data": {
"user": {
"name": "Ivan",
"email": "ivan@example.com"
}
}
}
2. Flexibility and scalability
REST works well in monolithic systems: its structure is clear and simple. However, in microservices REST can become a bottleneck.
For example, if a client needs to combine data from two microservices that expose different APIs:
- REST would require several sequential requests from the client.
- GraphQL allows the client to aggregate data from different sources in a single request.
Example:
query {
user(id: 123) {
name
orders {
id
total
}
}
}
This query will fetch user data and their orders (even if orders live in another microservice).
Pros and cons
REST
Pros:
- Simplicity. REST is familiar to most developers (chances are you've already used REST).
- Available tooling like Swagger/OpenAPI for documenting REST APIs.
- REST works well for small, fixed APIs and is stable in most scenarios.
Cons:
- Versioning: if you need to change the API, you have to introduce new versions (e.g.,
/v2/users). That can complicate the system over time. - Over-fetching and under-fetching: REST often returns too much or too little data, requiring extra requests.
- Not very convenient for microservice systems where data is often spread across multiple services.
GraphQL
Pros:
- Flexibility: the client requests only what it needs.
- Unification: a single access point to fetch all data.
- Works great with microservices: can combine data from different sources.
- Strong typing and developer ergonomics: the GraphQL schema serves as a "contract" between client and server.
Cons:
- Implementation complexity: it takes more time and resources to set up a GraphQL server and tooling.
- Potential performance issues: complex queries can strain the server if resolvers aren't optimized.
- Learning curve for new developers who are used to REST.
When to choose GraphQL vs REST?
GraphQL is better suited for:
- Client applications with dynamic user interfaces. For example, if you have a React/Vue app that needs to show different sets of data for different users.
- Microservices: GraphQL lets you "hide" the complexity of a microservice system behind a single façade.
- Complex queries and data aggregations: If your app frequently uses aggregated data from multiple sources.
REST is better suited for:
- Simple APIs: e.g., services that provide data that rarely changes.
- Resource-constrained systems: REST is simpler and requires less CPU/memory to handle requests.
- Caching scenarios: REST APIs are easy to cache at the HTTP level (e.g., via CDN), which GraphQL doesn't support "out of the box".
Hybrid architectures
As they say, why pick one when you can use both? A hybrid approach uses REST and GraphQL in the same project.
Example:
- REST for simple microservices where data doesn't require flexibility.
- GraphQL as a single façade for a complex microservice system.
Real-world scenario:
Suppose you have an e-commerce platform. Use REST for the auth microservice (/auth), and GraphQL for the product catalog microservice where the client needs to choose which product fields to request.
Potential problems
Both REST and GraphQL can cause issues if used incorrectly. With REST it can be too many or too few requests. With GraphQL it can be unoptimized resolvers and overly complex queries that overload the server.
Final recommendation
When choosing between REST and GraphQL consider your system's needs. If you're working with an established system or simple microservices, REST can be a great fit. If your system needs to be flexible, handle large amounts of data, and return customized responses, GraphQL will become your new best friend!
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