Why is Spring Bean Scopes (Singleton vs Prototype) recommended in production Java applications?

It guarantees immutability, prevents NullPointerExceptions, and simplifies unit testing with Mockito without starting slow test servers.

Spring Bean Scopes (Singleton vs Prototype) | Java Spring Boot Guide

Spring Bean Scopes (Singleton vs Prototype)

Understand Singleton, Prototype, Request, and Session bean scopes with beginner examples.

Written by Anuj Kumar Singh (Lead Engineer, 13+ yrs exp) • 5 min read • Verified Spring Boot 3+ Guide

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A Scope defines how long a bean lives and how many instances Spring creates.

Scope	How Many Instances?	Best Used For
Singleton (Default)	Exactly 1 shared instance per application	Services, Repositories, Controllers (Stateless classes)
Prototype	A NEW instance every time requested	Stateful objects holding unique data per request
Request (Web)	1 instance per HTTP Request	User Request tracking context
Session (Web)	1 instance per User HTTP Session	User Shopping Cart, Login Session