One of the biggest productivity boosters in Spring Boot is the concept of starters.
Starters eliminate the pain of manually selecting, versioning, and maintaining multiple dependencies.

This post explains what Spring Boot starters are, how they work internally, and how to use them effectively.

1. What Are Spring Boot Starters?

Spring Boot starters are predefined dependency descriptors that bundle commonly used libraries together for a specific purpose.

Instead of adding multiple dependencies manually, you add one starter.

Example:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

This single dependency brings everything needed to build a web application.

2. Why Starters Were Introduced

Before Spring Boot, developers had to:

• Find the right libraries
• Choose compatible versions
• Manage transitive dependencies
• Resolve version conflicts

Starters solve this by:

• Providing curated dependency sets
• Ensuring compatibility
• Reducing configuration
• Improving build stability

3. What Does a Starter Contain?

A typical starter includes:

• Core Spring modules
• Third-party libraries
• Transitive dependencies
• Version management (via Spring Boot BOM)

Importantly, starters do not contain code—only dependencies.

4. Commonly Used Spring Boot Starters

Here are some widely used starters:

5. Starter Dependency Internals (Example)

spring-boot-starter-web typically includes:

• Spring MVC
• Embedded Tomcat
• Jackson
• Validation API

All versions are aligned automatically.

6. Starters and Dependency Management (BOM)

Spring Boot uses a Bill of Materials (BOM) to control versions.

In Maven, this is handled automatically by:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
</parent>

This ensures:

• Consistent versions
• No dependency conflicts
• Easy upgrades

7. Using Starters with Gradle

In Gradle:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
}

Gradle also uses the Spring Boot dependency management plugin.

8. Custom Starters (Advanced Concept)

Large organizations often create custom starters to standardize:

• Logging
• Security
• Observability
• Internal libraries

A custom starter typically contains:

• Auto-configuration
• Dependency definitions
• Conditional beans

9. Best Practices

• Prefer starters over individual dependencies
• Avoid overriding versions unless required
• Remove unused starters
• Use spring-boot-starter-test for testing
• Upgrade Spring Boot to upgrade all dependencies safely

10. Summary

• Starters bundle related dependencies
• They simplify dependency management
• They ensure compatibility
• They speed up development
• They are a key reason Spring Boot is developer-friendly

Understanding starters helps you manage builds cleanly and confidently.

What's Next?

Next post:

22 - Spring Boot Configuration: application.properties & application.yml

We’ll explore how Spring Boot handles configuration and externalized settings.