JPlag vs Originality.ai

JPlag is free, open-source software for finding pairwise similarities among submitted programs. It examines program syntax and structure to help detect source-code plagiarism and collusion, especially in student programming exercises, and can also identify duplicated or stolen software parts. It does not compare submissions with the internet. Supported inputs include Java, C, C++, C#, Python, JavaScript, TypeScript, Go, Kotlin, R, Rust, Swift, Scala, LLVM IR, Scheme, EMF, SCXML, text, and multi-language projects. JPlag runs locally, with the project stating that source code and plagiarism results are not sent externally. You can use its command-line interface, Java API, or Maven Central dependency. A bundled report viewer opens generated or existing reports. Base-code directories can exclude shared starter code, while matching-token sensitivity is adjustable. The default report lists up to 2500 comparison pairs, configurable with -n. Running or building it requires Java SE 25.

Originality.ai provides tools for checking AI-generated text, plagiarism, facts, readability, grammar, spelling and content quality. Its free Basic plan costs $0.00 per free and provides three AI scans per day, with up to 2,000 words per scan. The AI detector offers configurable allowances of 0%, 5%, 15%, 25% or 40%. A website scanner can crawl a site, identify pages likely to contain AI-generated content and run scheduled scans. The browser extension scans Google Docs, web pages or selected text, and includes writing replay, typing behavior insights and shareable reports. A REST-based API submits text for AI and plagiarism scans and returns detailed results; the maker says AI detection supports 30 languages. API AI scans require at least 50 words, and the help page says accuracy decreases below 100 words. Originality.ai describes detection results as probabilistic estimates that may produce false positives or false negatives, not conclusive proof. Pro costs $12.95 per month billed yearly, with a monthly option at $14.95 per month. The service is available through web, API and extension.