Does HackerRank Detect Plagiarism in Your Code?
2026-09-08
Plenty of common problems have one obvious solution. So it is fair to worry that your honest answer will look like someone else's and get you flagged.
Here is the straight answer.
Yes. HackerRank checks coding answers for plagiarism on every test by default using MOSS, a code similarity tool. Companies can also turn on an optional AI model that looks at how you wrote the code as well.
MOSS: on by default
HackerRank says "MOSS plagiarism detection is turned on by default for all HackerRank tests."
MOSS breaks your code into tokens and compares them with other submissions to find large overlaps. HackerRank says renaming variables or adding white space is generally ineffective as a way around it, because MOSS focuses on the structure of the code.
Reviewers see a match percentage, grouped as High, Medium, or Low.
AI plagiarism detection: optional
The second model is something the company can enable if it wants. It currently supports only Coding questions.
HackerRank lists the signals it considers, including:
- Code writing patterns
- Time taken to solve the problem
- Copy-paste activity
- Tab-switching behavior
The model classifies flagged attempts as High or Medium. When it is enabled, candidates must consent before starting the test, so you will know.
HackerRank says this model is especially useful for spotting AI tools like ChatGPT when a test restricts them. More on that in does HackerRank detect ChatGPT.
What the hiring team sees
Flagged attempts show up in the candidate report. Reviewers can watch a Keystroke Codeplayer to see the relevant parts of your coding session.
For MOSS flags, the reviewer checks the flagged code and confirms or dismisses the flag. HackerRank also notes that MOSS cannot determine the exact source of plagiarism, and recommends reviewing the code playback first.
What this means for you
A similar answer is not an automatic fail. A person reviews the flag. The strongest thing you can do is write the code yourself in the editor, step by step, so your playback shows real work.
Writing your own solution with support
StealthCoder is a desktop app that runs separately from the browser. It reads the problem on screen and helps you work through it, so the code you type is still yours.
You've read the playbook.
Now make sure you pass the live OA.
Knowing the patterns isn't the same as solving them under a timer with a proctor watching. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.