Spring Boot 4.0: Enterprise Java Framework for Microservices

Quick Answer

Spring Boot is Java’s premier framework for building production-grade applications, particularly enterprise microservices. Version 4.0 (November 2025) introduces GraalVM native image compilation, eliminating the JVM startup penalty and enabling cloud-native deployments. Its modular architecture, comprehensive ecosystem, and enterprise support make it the standard for Java development in 2026.

What is Spring Boot?

Spring Boot simplifies Spring framework development by providing opinionated defaults and auto-configuration. It eliminates boilerplate while maintaining the flexibility to override defaults as needed.

Version 4.0 Highlights

Key Features:

• GraalVM native image support
• Modular auto-configuration JARs
• Declarative HTTP clients (Feign replacement)
• Built-in resilience patterns (@Retryable, @ConcurrencyLimit)
• OpenTelemetry integration (spring-boot-starter-opentelemetry)

Release: November 20, 2025

Maintainer: VMware (Pivotal)

Core Architecture

GraalVM Native Images

AOT Compilation:

• Startup: 80ms (vs 4-10s JVM)
• Memory: 40-60MB (vs 200MB+)
• No runtime compilation overhead

Trade-offs:

• Slower build times
• Closed-world assumption (reflection restrictions)

Modular Auto-Configuration

Before (Monolithic):

• Single spring-boot-autoconfigure JAR
• All tech configurations bundled

After (Modular):

• Focused JARs per technology
• Faster startup, smaller memory footprint
• Better tree shaking

Platform Support

Platform	Support	Details
Web	✅ True	SSR (Thymeleaf/FreeMarker)
API	✅ True	RESTful APIs
Microservices	✅ True	Built-in support
Serverless	✅ True	Spring Cloud Function

Key Features

1. Dependency Injection

@Service
public class UserService {
    private final UserRepository repo;
    
    public UserService(UserRepository repo) {
        this.repo = repo;
    }
}

2. REST Controllers

@RestController
@RequestMapping("/api/users")
public class UserController {
    
    @GetMapping("/{id}")
    public ResponseEntity<User> getUser(@PathVariable Long id) {
        return ResponseEntity.ok(userService.findById(id));
    }
}

3. Data Access (Spring Data JPA)

public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findByLastName(String lastName);
}

Spring Boot vs Node.js

Feature	Spring Boot	Node.js
Architecture	Multi-threaded	Single-threaded Event Loop
Best For	CPU-intensive, Enterprise	I/O-intensive, Real-time
Performance	High (peak throughput)	High (concurrency)
Scalability	Vertical + Horizontal	Horizontal (process clones)

Best Use Cases

Ideal For

• Financial systems
• Enterprise applications
• Microservices (Spring Cloud)
• Complex business logic

Avoid For

• Simple CRUD APIs (overkill)
• I/O-bound real-time apps (Node.js better)
• Low-memory serverless (startup overhead)

Conclusion

Spring Boot 4.0 represents the maturation of enterprise Java development. GraalVM native images eliminate the JVM startup penalty, making Java viable for serverless and edge deployments. The modular architecture and comprehensive ecosystem ensure it remains the standard for enterprise Java development.

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Last Updated: 2026-01-20