Does Codility Detect Plagiarism in Your Code?

2026-09-22

You wrote a solution that looks a lot like the textbook version. Now you are wondering if Codility will call it plagiarism.

Here is how it works.

Yes, Codility checks code for plagiarism with a tool called Similarity Check. It compares your solution with other candidates' submissions, leaked solutions found online, and AI-generated answers. A match is a flag for review, not an automatic fail.

What Similarity Check compares

Codility says "Similarity Check automatically cross-checks your candidates' solutions against every other submission we've received."

It also looks outside the platform. "We also scrape the web for leaked solutions."

Renaming things does not hide a copy. Codility says its system "can recognize similarities even if solutions have been modified (e.g., changing identifiers, reformatting code, or making small changes in the code structure)."

On AI, "the submitted solutions are cross-referenced against AI-generated solutions."

When it runs

This is not a premium add-on. Codility says "Network IP Detection and Plagiarism Detection are available to all customers."

It does not run on every submission, though. If the test has no passing score, Codility checks "all candidates who scored at least 40% on the task."

Some task types are skipped entirely, including:

• Multi-file project tasks
• Bugfixing tasks
• Multiple-choice and essay questions
• SQL tasks
• VS Code content

What the hiring team sees

Results show up in the Plagiarism section of the candidate report. If the match comes from a company outside the hiring team's account, the other solution is shown simply as "another candidate".

Codility tells reviewers a flag is not proof: "The warning doesn't necessarily suggest cheating." It also admits some tasks "are too simple to discern whether candidates cheated or that the similar submissions are merely coincidental."

Codility also says AI does not decide the flag: "We do not use AI to decide whether a solution should be flagged as potentially plagiarized." For how other platforms handle this, see does CodeSignal detect cheating.

Writing code that is actually yours

The safest code is code you reasoned through yourself. Copied code from another candidate or a leaked answer is what this check looks for.

StealthCoder is a desktop app that runs separately from the browser. It reads the problem on your screen and helps you work through the logic, so the code you type is your own.