Dolos vs Simian Similarity Analyzer

Dolos is a free, open-source tool for finding similarities between source-code submissions, particularly for teachers reviewing tests, exams, and exercises where collaboration may be allowed in small groups. Its analysis process tokenizes files, fingerprints token sequences, indexes matches, and produces reports. For each file pair, reports include similarity, total overlap, and the longest matching fragment. Dolos uses Tree-sitter parsers and supports languages including Bash, C, C++, C#, Elm, JavaScript, Java, PHP, Python, and TypeScript. The web app accepts ZIP files and detects languages from file extensions; in mixed-language archives, it analyzes only the dominant language unless a language is selected. Its public API accepts ZIP submissions up to 10 MB, with the CLI or library recommended for larger submissions. Analyses can also run locally, with results displayed in a browser, or on a self-hosted server. The free web app is hosted on Ghent University servers in Belgium. Dolos provides a JSON API for integrations such as Dodona and lists CSV as a report export format.

Simian Similarity Analyzer scans files in a repository and reports repeated blocks of text, including duplicated code. It analyzes human-readable material such as source files, markup, stylesheets, Markdown, and plain text. Listed languages range from Java, C, C++, C#, COBOL, and Python to JavaScript, TypeScript, HTML, XML, and CSS. The tool runs on the Java Virtual Machine, and its generated JAR works with JDK 8 or newer. It can run locally, from scripts, or in a build pipeline; the repository also documents Gradle integration. Results are plain text by default, with XML, YAML, and editor-friendly formats available. Settings include a duplicate-line threshold, file include and exclude patterns, language selection, and ways to ignore differences such as identifiers, strings, and numbers. The maker reports a JDK test processing over 2.4 million lines and finding more than 140,000 duplicate lines in under five seconds, with results varying by hardware, operating system, and options. Simian is free and open source under Apache License 2.0.