RestClient vs. WebClient vs RestTemplate

Using the suitable library to call REST API in Spring ‌Boot

I recently wrote an article about how to use WebClient synchronously in the Spring Web MVC stack and described if it is a good idea to call the WebClient block() operation in this case:

Using WebClient synchronously in Spring Web MVC stack

But after releasing Spring Boot 3.2, the story of calling REST APIs from a Spring Boot application has become even more complicated. By releasing Spring Boot 3.2, another new library has entered the game in this area: the RestClient library.

In this article, I will compare these three libraries for calling REST APIs in Spring Boot applications. I will also give some recommendations of which one is the right choice for different situations.

· What does RestTemplate lack from its competitors?
∘ Calling the echo service using RestTemplate
∘ RestTemplate supports the declarative HTTP interface!
∘ RestTemplate pros and cons
· What did WebClient bring us new?
∘ Calling the echo service using WebClient
∘ Defining declarative HTTP interface using WebClient
· Yet another HTTP client library for Spring Framework. Why?
∘ Calling the echo service using RestClient
∘ Migrate from RestTemplate to RestClient
∘ Defining declarative HTTP interface using RestClient
· Final comparison and advice
· Observe HTTP client calls using Digma
∘ Sample application services
∘ Observe HTTP Client's Activities and Traces locally using Digma
· Final Thoughts

What does RestTemplate lack from its competitors?

Before the emergence of the WebFlux stack, RestTemplate was the best choice to have a full-fledged synchronous HTTP client library for the Spring Framework since version 3.0. Before starting to know why we need to have another HTTP client library in Spring Framework, let’s get to know RestTemplate and its pros and cons.

In our example in this article, We have a hypothetical service called echo-service that provides echo REST API (using HTTP GET), and we want to call that API using these three libraries that Spring Boot provides us to see differences and similarities (you can find more description and the GitHub…