Quarkus vs Spring Boot: What are the differences?

Introduction

Quarkus and Spring Boot are two popular frameworks for developing Java applications. While both frameworks allow developers to build high-performance, lightweight, and scalable applications, there are some key differences that distinguish them from each other.

1. Containerization: One key difference between Quarkus and Spring Boot is their approach to containerization. Quarkus is designed specifically to run natively in a containerized environment, using technologies like GraalVM and SubstrateVM. This allows Quarkus applications to start up faster, use less memory, and have lower resource requirements compared to Spring Boot applications. In contrast, Spring Boot is more focused on supporting the full Java runtime stack and can be deployed in traditional non-containerized environments as well.

2. Runtime footprint: Quarkus has a significantly smaller runtime footprint compared to Spring Boot. This is achieved by optimizing the framework for containerization and eliminating unnecessary dependencies. Quarkus applications are more lightweight, which means they consume less memory and start up faster. Spring Boot, on the other hand, has a larger runtime footprint due to its support for a broader range of features and integrations.

3. Development model: Quarkus and Spring Boot have different development models. Quarkus promotes the use of a reactive programming model, where developers write non-blocking, event-driven code to achieve high scalability and responsiveness. It leverages standards like Reactive Streams and Eclipse Vert.x to provide a reactive programming experience. Spring Boot, on the other hand, follows a more traditional imperative programming model, where developers write blocking code and use annotations and configuration to achieve functionality.

4. Micronaut AOT support: Quarkus has built-in support for Ahead-of-Time (AOT) compilation, thanks to the integration with GraalVM and SubstrateVM. This allows Quarkus applications to be compiled ahead of time into a native executable, resulting in faster startup times and reduced memory consumption. In contrast, Spring Boot does not have built-in AOT support but can be used with GraalVM in combination with the Spring Native project to achieve similar benefits.

5. Ease of testing: Both Quarkus and Spring Boot provide test support, but they differ in their approach. Quarkus comes with built-in test utilities that enable easy and efficient testing of Quarkus applications. It provides a test framework that can run native tests, allowing developers to test their applications in the same environment they will be deployed in. Spring Boot, on the other hand, has a more mature and extensive testing ecosystem, with support for various testing frameworks and tools like JUnit, Mockito, and Spring Test.

6. Ecosystem and community: Spring Boot has a larger ecosystem and community compared to Quarkus. It has been around for a longer time and has a well-established community with a wide range of resources, libraries, and integrations. Spring Boot's ecosystem is known for its robustness and extensive documentation. Quarkus, being a relatively new framework, is still growing its ecosystem and community, but it is backed by Red Hat and benefits from its strong support.

In summary, Quarkus and Spring Boot differ in their approach to containerization, runtime footprint, development model, AOT support, ease of testing, and ecosystem/community. Quarkus is geared towards containerized environments, has a smaller footprint, promotes a reactive programming model, and has built-in AOT support. Spring Boot, on the other hand, is more versatile, has a larger runtime footprint, follows a traditional imperative programming model, can be used with GraalVM for AOT compilation, and has a more mature testing ecosystem and established community.