Checkstyle is a tool for checking Java source code for adherence to a Code Standard or set of validation rules (best practices).
Members chat: 
The latest release version can be found at GitHub releases or at Maven repo.
Each-commit builds of maven artifacts can be found at Maven Snapshot repository.
Documentation is available in HTML format, see https://checkstyle.org/checks.html.
Explanation on how to create your own module
Travis (Linux & MacOS build):
Quality reports: https://checkstyle.org/project-reports.html
JavaScript, CSS and Java source file analysis on Codacy:
Please send any feedback to https://groups.google.com/forum/?hl=en#!forum/checkstyle
Questions and Answers from community:
Bugs and Feature requests (not the questions): https://github.com/checkstyle/checkstyle/issues
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This software is licensed under the terms in the file named "LICENSE" in this directory.
The software uses the ANTLR package (https://www.antlr.org/). Its license terms are in the file named "RIGHTS.antlr" in this directory.
This product includes software developed by The Apache Software Foundation (https://www.apache.org/).
The software uses the Logging and Beanutils packages from the Apache Commons project (https://commons.apache.org/). The license terms of these packages are in the file named "LICENSE.apache20" in this directory.
The software uses the Google Guava Libraries (https://github.com/google/guava/). The license terms of these packages are in the file named "LICENSE.apache20" in this directory.
The software uses the Picocli Library (https://github.com/remkop/picocli/). Its license terms are in the file named "LICENSE.apache20" in this directory.