copydetect vs PMD

copydetect is a free tool for comparing code directories and producing an HTML report that highlights matching code slices. It uses Winnowing document fingerprinting, an approach also used by MOSS, and Pygments tokenization for the 500-plus languages Pygments can detect and tokenize. Users can compare test directories with reference directories such as previous submissions, and exclude boilerplate directories from matches. Noise, guarantee and display thresholds adjust what is detected and shown in reports. Install the package with pip; it requires Python 3.7 or later. The command-line tool recursively searches supplied directories, while its Python API supports comparisons and HTML report generation. Reports can be saved to a specified path, highlighted code can be truncated, and custom CSS can be linked. Configuration is available through command-line arguments or a JSON file. The package is MIT-licensed and classified for Education with Beta development status. Its documentation cautions that it may not catch plagiarism designed to evade detection and that a match does not establish that plagiarism occurred.

PMD is a free, extensible static code analyzer that checks source code for programming flaws such as unused variables, empty catch blocks, and unnecessary object creation. It includes more than 400 built-in rules, and teams can write custom rules in Java or XPath. Its bundled CPD tool finds duplicated code across many programming languages. PMD checks source directories from the command line and can run as a Maven, Ant, Gradle, or bld build operation. Supported languages include Java, JavaScript, Salesforce Apex and Visualforce, Kotlin, Swift, Modelica, PL/SQL, Apache Velocity, JSP, WSDL, Maven POM, HTML, XML, and XSL; Scala is supported without Scala rules. It runs on Linux, macOS, and Windows and requires Java 8 or above. For CI, its GitHub Action can create SARIF reports and fail builds based on violation counts; documentation also covers GitLab, Jenkins, and Bamboo integrations. IDE integrations include Eclipse, IntelliJ IDEA, and Visual Studio Code, though some listed plugins are not actively maintained. Only the latest major version is actively developed.