Starters and the BOM

Curated dependency bundles and how the Spring Boot BOM keeps versions aligned.

Intermediate9 min read

Read these first

How Auto-Configuration Works

Why this matters

Starters are how Boot keeps BookStore dependencies aligned — one starter, zero version numbers.
The BOM (Bill of Materials) pins compatible versions across the entire Spring ecosystem.
Choosing the wrong starter (web vs webflux) shapes your entire application architecture.

How starters work

A starter POM contains only dependencies — no application code:

Java

<!-- spring-boot-starter-web internally depends on: -->
<!-- spring-boot-starter, spring-boot-starter-json, -->
<!-- spring-boot-starter-tomcat, spring-web, spring-webmvc -->

Your BookStore pom.xml declares intent:

Java

<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
  </dependency>
</dependencies>

No version tags — the parent BOM supplies them.

spring-boot-starter-web

spring-boot-starterCore Boot + logging

spring-webmvcControllers and REST

tomcat-embed-coreEmbedded server

jackson-databindJSON serialisation

spring-boot-starter-web pulls in Tomcat, Jackson, Spring MVC and more with tested versions.

Starters BookStore uses

spring-boot-starter-web — Tomcat, Spring MVC, Jackson JSON.
spring-boot-starter-data-jpa — Hibernate, Spring Data JPA, JDBC, connection pool.
spring-boot-starter-validation — Hibernate Validator for @Valid on DTOs.
spring-boot-starter-security — Spring Security filter chain.
spring-boot-starter-test — JUnit 5, Mockito, AssertJ, MockMvc.

The Spring Boot BOM

spring-boot-starter-parent imports spring-boot-dependencies — a BOM listing every managed version:

Java

<parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>3.4.1</version>
</parent>

Override a single version when needed:

Java

<properties>
  <flyway.version>10.4.0</flyway.version>
</properties>

The property name matches the BOM key. Avoid overriding Spring Framework versions — mismatches cause runtime NoSuchMethodError.

Starter naming convention

Pattern	Meaning
spring-boot-starter-{name}	Official Boot starters
spring-boot-starter-{name}-test	Test slice for a technology
{group}-spring-boot-starter	Third-party starters (e.g. springdoc)

spring-boot-starter-{name}
MeaningOfficial Boot starters
spring-boot-starter-{name}-test
MeaningTest slice for a technology
{group}-spring-boot-starter
MeaningThird-party starters (e.g. springdoc)

Third-party starters follow the same auto-config pattern but are not in the BOM — check their docs for compatible Boot versions.

Inspecting transitive dependencies

Java

./mvnw dependency:tree -Dincludes=org.hibernate

Shows exactly which starter pulled in Hibernate and at what version. Use this when resolving conflicts.

Test starter scope

Java

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

Test-scoped dependencies never appear in the production JAR. They include:

Common test dependencies

JUnit Jupiter
Mockito
AssertJ
Spring Test (@SpringBootTest, MockMvc)
JSONassert

Optional: spring-boot-starter-actuator

Java

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

Adds /actuator/health and /actuator/metrics — essential for production BookStore deployments. Covered in the observability module.

Version alignment in multi-module builds

Parent POM for a BookStore monorepo:

Java

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-dependencies</artifactId>
      <version>3.4.1</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

Child modules inherit versions without using spring-boot-starter-parent as their direct parent.

Quick recall

Everything you need if you only revisit this box.

Starters bundle related dependencies; you declare capability, not individual JARs.
spring-boot-starter-parent imports the BOM that pins all managed versions.
Never specify versions for BOM-managed dependencies unless overriding deliberately.
spring-boot-starter-test is test-scoped and includes JUnit, Mockito, and MockMvc.
Use dependency:tree to trace which starter pulled in a conflicting library.
Do not mix web and webflux starters without a deliberate architectural reason.

Test yourself

Answer these before moving on — recall is what makes it stick.