JPlag
- Android app
- Not listed
- Free plan
- Yes
- Runs on
- api, Linux, Mac, self-hosted, Windows
Summary
JPlag compares programs with one another to identify pairwise similarities that may indicate source-code plagiarism or collusion. It examines programming-language syntax and program structure, which can reveal matches even when code has been partly obfuscated. The project says analysis runs locally and sends no data externally; it does not check submissions against internet sources. Its listed language support includes Java, C, C++, C#, Python, JavaScript, TypeScript, Go, Kotlin, R, Rust, Swift, Scala, LLVM IR, Scheme, EMF, SCXML, text, and multi-language submissions, with varying maturity. Users can work through a command-line interface or Java API; the CLI can also launch a report viewer. JPlag is available through Maven Central for use as a Java project dependency. It is free, but running or building it requires Java SE 25. By default, the report’s top list and code comparison include up to 2,500 pairs, adjustable with the -n option. Reducing the minimum matching-token length raises sensitivity but can also raise false positives.
Who it is for
JPlag suits educators comparing programming submissions and developers looking for duplicated or modified software components. It is also a fit for users who need local analysis and can meet its Java SE 25 requirement.
What is good
- Analysis runs locally, with no external data sent.
- Compares syntax and program structure.
- Provides a command-line interface and Java API.
- Supports a broad set of languages and formats.
- Free to use.
What to know first
- Does not compare submissions against the internet.
- Requires Java SE 25 to run or build.
- Language support maturity varies.
- Lower token thresholds can increase false positives.
Verdict
JPlag is a free option for pairwise code comparison, with local processing and several ways to integrate or run it. Its internet-search limitation and Java requirement are important considerations.
JPlag plans and pricing
All plansCompared on plagiarism detection software
- Free plan
- Yesgithub.com
- AI detection
- Nogithub.com
- LMS integrations
- Nogithub.com
- API access
- Yesgithub.com
- Browser extension
- Nogithub.com
Facts
- Purpose
- JPlag finds pairwise similarities among programs to detect source-code plagiarism and collusion.github.com · 29 Sept 2026
- How it compares
- It analyzes programming-language syntax and program structure, which helps it detect similarities despite some obfuscation attempts.github.com · 29 Sept 2026
- Local processing
- The project says analysis runs on the user's machine and sends no data externally.github.com · 29 Sept 2026
- No internet search
- JPlag compares submissions with one another and does not compare them against the internet.github.com · 29 Sept 2026
- Languages
- The README lists support for Java, C, C++, C#, Python, JavaScript, TypeScript, Go, Kotlin, R, Rust, Swift, Scala, LLVM IR, Scheme, EMF, SCXML, text, and multi-language submissions, with varying maturity levels.github.com · 29 Sept 2026
- Interfaces
- JPlag can be used through its command-line interface or Java API, and the CLI can launch the report viewer.github.com · 29 Sept 2026
- Integration
- JPlag is published on Maven Central for inclusion as a dependency in Java projects.github.com · 29 Sept 2026
- Report limit
- The report's top list and code comparison include at most 2,500 pairs by default; this limit can be changed with the -n option.github.com · 29 Sept 2026
- Sensitivity
- Lowering the minimum matching-token length increases sensitivity but may also increase false positives.github.com · 29 Sept 2026
- Use cases
- The project describes use in programming education and says it can also identify duplicated or slightly modified software parts.github.com · 29 Sept 2026
- Runtime requirement
- The README says Java SE 25 is required to run or build JPlag.github.com · 29 Sept 2026
- Support
- The project directs users to report bugs and issues on GitHub and provides a Q&A discussion section.github.com · 29 Sept 2026
- Project history
- JPlag was originally developed at Karlsruhe Institute of Technology in 1996 and is maintained primarily by KIT researchers.github.com · 29 Sept 2026
Company
- Founded
- 1996github.com · 28 Sept 2026
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Sources
- github.com/jplag/JPlag/wiki· checked 29 Sept 2026
- github.com/jplag/JPlag/blob/main/README.md· checked 29 Sept 2026
- github.com/jplag/JPlag· checked 28 Sept 2026