Simian Similarity Analyzer

Simian Similarity Analyzer finds repeated text blocks across repositories, making it a practical choice for developers who want configurable clone checks in local workflows or build pipelines. Its broad file coverage and scriptable use are appealing, though the Java runtime and lack of IDE integration narrow its fit.

Overview

Simian scans repositories for duplicated blocks in source code and other human-readable files. That includes markup, stylesheets, Markdown, and plain text, which helps teams find repetition that crosses the usual boundaries of a code-only scan. Its detection method is text-based, so it is best understood as a way to identify repeated content, not as a general-purpose code analyzer.

The tool runs on the Java Virtual Machine, and its generated JAR runs on JDK 8 or newer. Developers can invoke it locally, from scripts, or in a build pipeline; the repository also documents a Gradle task for scanning project source files. This flexibility suits teams that want to add clone checks to existing automation, but the JVM requirement is an extra dependency for workflows that do not already use Java.

Key features

Tunable duplicate detection

Users can set a minimum duplicate-line threshold, include or exclude files by pattern, select languages, and tell Simian to ignore identifiers, strings, numbers, or other differences. These controls help teams decide whether to focus on close textual matches or surface broader repetition. The trade-off is that scan quality depends on tuning options to the repository; a threshold or ignore rule that is too broad or too narrow can change which matches matter.

File coverage and output

Named language support spans Java, C, C++, C#, COBOL, Python, Ruby, PHP, JavaScript, TypeScript, HTML, XML, CSS, Sass, Less, Visual Basic, and Groovy. Results default to plain text, with XML, YAML, and editor-friendly formats also available. The range of formats gives pipeline users ways to consume or route output, while the default remains straightforward for a local review.

Performance and integration

The maker reports that a JDK test processed more than 2.4 million lines and found over 140,000 duplicate lines in under five seconds, with results dependent on hardware, operating system, and options. That is an encouraging scale signal, not a guarantee for every repository. Documented Gradle integration and CI support make Simian a sensible candidate for repeatable checks; teams looking for IDE integration should choose another workflow or tool.

Pricing

Simian Similarity Analyzer costs nothing. It is open source under the Apache License 2.0, with a free plan and a self-hosted option. There are no paid tiers to weigh against reduced capabilities; in return, users take on the setup of the Java runtime and their own scan configuration. The maker directs users to Stack Overflow for help and welcomes feedback and contributions on GitHub.

Platforms

Simian is available for Linux, macOS, and Windows. Its JVM-based JAR and JDK 8-or-newer requirement provide a consistent runtime basis across those desktop and server environments, while the documented build-pipeline use fits teams running scans as part of CI.

Who it's for

Simian is best suited to developers and teams that want repository-wide, configurable duplicate detection across code and other readable files, especially when they can run checks locally or automate them in a build pipeline. It is a weaker fit for users who need IDE integration, or for teams seeking analysis beyond text-based clone detection.

Pros and cons

• Pros: Scans source code, markup, stylesheets, Markdown, and plain text, giving mixed repositories a wider scope than source-only checks.
• Pros: Threshold, file-pattern, language, and ignore controls let teams tune which repetitions count.
• Pros: Local, scripted, Gradle, and CI use support both individual scans and repeatable pipeline checks.
• Cons: Requires a Java runtime, with the generated JAR requiring JDK 8 or newer.
• Cons: No IDE integration, so it does not suit teams that need clone findings embedded in an editor workflow.
• Cons: Text-based detection and configurable rules mean it is not a substitute for broader code analysis, and useful output depends on appropriate tuning.

Alternatives

Code Clone Detection Tools is the category directory for comparing tools in this area.

• Duplo is another free option for Linux, macOS, and Windows, distributed under GNU GPL v2 or later.
• PMD is a free static code analyzer for Linux, macOS, self-hosted environments, and Windows; choose it when static analysis is the priority rather than Simian's text-based clone detection.
• CloneWorks is free for Linux, macOS, and Windows, but its terms require acknowledgement and free redistribution and derivatives.
• dcd is a free AGPL-3.0 option for Linux and macOS; a priority-support plan is also offered, billed a years worth, with direct email support from the developer.
• jscpd is a free alternative with Linux, macOS, self-hosted, Windows, and API platforms.
• NiCad is free and open source under the MIT license, runs on Linux, macOS, self-hosted environments, and Windows, and requires OpenTxl 11 or later.
• CopyPaste is a free and open-source option for macOS and Windows with no premium tiers, subscriptions, or paywalls.
• Algo VPN is a free, self-hosted VPN setup tool rather than a code-clone detector, so it serves a different need.

Verdict

Choose Simian if you want free, configurable text-based clone detection across a repository and value local or pipeline use, including documented Gradle integration. Its broad file scope is the main reason to choose it; look elsewhere if Java-runtime setup or the absence of IDE integration conflicts with your workflow.