Open Source Code Quality Tools For Java

Do you want to learn about open source code quality tools for java? Are you a developer who wants to know the top code quality tools that they should be using? If so, this comprehensive post will help you tremendously.

Here I’ll share with you some open source code quality tools for java to improve the quality of your code in a very short time. Let’s face it — anyone can write bad code that meets their immediate need but only those that deliver quality code can be the difference between success and failure. That is why, to be an excellent programmer, you need to write code that works perfectly and is extremely reliable.


DeepSource delivers what is probably the best static code analysis you can find for Java. The DeepSource Java analyzer detects 190+ code quality issues, including performance bugs, security risks, bug risks, and anti-patterns. Currently, It supports Gradle Java projects, and in the future, DeepSource will add support for Maven and Android too. DeepSource is also working on bringing Autofix support to the Java analyzer, which will let developers fix issues without writing a single code line.


  • Detects more than 170 code quality issues.
  • OpenJDK versions 8 to 14 are currently supported.

Integration: Gradle

Licensing: Free to use for open-source, Students, and Non-Profit Organisations. Paid plans starts from 12 USD user/month.


JArchitect, a static Java source code analysis tool, evaluates Java code for complexity. It offers features such as code querying, enabling custom code, technical debt evaluations to identify the cost of fixing – or risk of not fixing – an error, and pass/fail quality gates. The tool also provides standard metrics and statistical analysis of the code.

In addition to those features, JArchitect can also identify code metrics like cyclomatic complexity (number of possible execution paths), source code lines, afferent (incoming) and efferent (outgoing) coupling, nesting, and depth. The software generates reports that help proactively guard against unplanned code errors.


Checkstyle is a tool that is used to check Java Source Code for Code standard or validation rules affirmation. It automates the Java code analysis process. Moreover, it is profoundly configurable and can support nearly every coding standard. Checkstyle will help you in detecting class design problems, formatting issues, and method design problems while checking code layout as well.

The standard checks for Checkstyle can be applied to general Java code with no need for external libraries. It is directly applicable to source code. You can access the standard check from Checkstyle, which is written in alphabetical order for ease of navigation.


Another free and open source Java code review tool is FindBugs. Also a static analyzer, this tool scans the code to find defects (or “bugs”), inconsistencies, or security threats in suspicious code sections. FindBugs identifies inconsistencies as warnings, allowing the developer the discretion to review the messages to determine whether they need to take corrective action. Developers can action the warning messages in this Java code review tool either individually or in batches. FindBugs requires JRE 1.7.0 or later to run and analyze any version of Java from 1.0 to 1.8.

SpotBugs is the next generation of FindBugs. Like the original, SpotBugs calls out warnings and developers can choose if they want to action them. SpotBugs lists both performance issues and Java code defects in the warnings section; as a result, not all warnings need to be changed. However, the tool does rank warnings into four categories to aid developers in their decision-making: “of concern,” “troubling,” “scary,” and “scariest.”


SonarQube is the open-source suite of java static code analysis tools that combines the features of tools such as FindBugs and PMD. SonarQube has very intuitive dashboards that maintain history to help developers track Java code quality over time. SonarQube uses advanced techniques like pattern matching and dataflow analysis to analyze code and identify code smells, bugs, and security vulnerabilities.


  • It has 597 rules to detect various code quality issues.
  • Java language versions supported up-to 14.


Infer is another useful static analysis tool for code in java but can also be used in C, C++, or Objective-C. It can be used to deflect bugs from reaching the end-users. With the assistance of Infer, one can easily prevent bad performance or crashes. In Java codes, infer identifies resource leaks, missing lock guards, null pointer exceptions, and annotation reachability. You can get the complete guidelines on getting started with detecting errors or faults from Infer.


The Graudit code review tool supports Java and other languages like Python, Perl, .NET, C, and PHP. It provides script and signature sets to help developers locate potential security vulnerabilities within Java code. In addition, the tool incorporates an extensive database of known flaws for comparison with the source code and calls out a positive match when the source code matches a database pattern. Graudit is found on Github and is maintained and updated regularly for maximum impact.

Graudit offers the ability for a user to add their database for analysis against the source code and compare multiple source code files at a time or just a single one. It is portable and flexible, offering a friendly user experience and lower technical and computational requirements than many other tools. This flexibility allows Graudit to run on most systems.


EclEmma(based on the JaCoCo library) is a free Java code coverage tool for Eclipse. It is a toolkit for measuring code coverage in a java code base and presenting coverage data through visual reports. It highlights the lines of code and the total percentage of code executed, and tracks both line and branch coverage. EclEmma helps developers assess code that has not been adequately tested and focuses on low coverage areas. It supports 3 types of report formats: HTML, XML & CSV.


  • Supports Java class files from version 1.0 to 14.

Integration: Ant, Maven.


Snyk Code is a novel static Java code review tool that statistically analyzes Java source code for security vulnerabilities while the developer codes. This tool performs automated secure code reviews rapidly and reduces false positives in the process.

Snyk’s Static Application Security Test (SAST) tool is more efficient than other tools and uses semantic analysis to find more vulnerabilities sooner to accelerate code development. This enables development teams to shift security left without compromising on speed. Snyk also offers a free pricing option for teams looking to quickly and easily get started with SAST.


JUnit is a popular unit testing framework for Java development projects that allows developers to write and run unit tests for Java 8 and above. JUnit tests the state and the behavior of the code with simple yet powerful assertion statements. It is easy to get started with JUnit, and It offers a variety of additional features using annotations for more complex scenarios.


  • JUnit 5(latest release) requires Java 8 (or higher) at runtime.

Integration: Maven, Gradle, Ant


In a nutshell, these tools can guide programmers in their journey of developing software, web-application, or website with ease. By saving time spent on fixing the entire code, these tools increase productivity.

Part of the joys of using open source software is that you get to use code that’s been carefully crafted and peer-reviewed. Of course, this also means there are plenty of errors to be found too. This is why it’s important to learn how to find and fix bugs in code. To help you with this, we’ve put together a list of open source code quality tools for Java.

The tools that have been recommended here are based on a few past experiences and preferences. So, the tools you choose must be according to the amount of testing and requirements of the project on which you are working


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