Notes from an open engine.
How Noplag detects plagiarism, what it honestly can't do yet, and why the code that decides is public. Written by the people who build it.
The honest limits of verbatim detection
Our engine detects verbatim and near-verbatim copying. It does not detect paraphrase. Every plagiarism checker has this boundary — we're just the ones who put it in writing.
Self-hosting Noplag on your own hardware
Three commands get you a working plagiarism checker that never sends a document anywhere. Here's who should self-host, what it takes, and the trade-offs nobody puts on the pricing page.
How Noplag detects plagiarism: winnowing fingerprints, explained
The algorithm that finds copied text across more than 150 million documents fits in about thirty lines of Python. Here's how winnowing works and why we chose it.
Why we open-sourced our plagiarism engine
Every plagiarism checker asks you to trust a score it won't explain. We published our detection engine so you don't have to take our word for anything.