Checkstyle

Checkstyle is a development tool that checks Java source code against a coding standard. Out of the box it supports the Google Java Style and Sun Code Conventions, and rules are configurable. Checks cover naming conventions, imports, Javadoc, formatting and whitespace, class design, coding practices, annotations and metrics.

Checkstyle runs from the command line and integrates with Maven, Gradle, Ant, IDEs such as Eclipse, IntelliJ IDEA and NetBeans, and CI tools. It is distributed under the GNU LGPL; version 14.3.0 was released in September 2026 and requires Java 21 or later.