Does Codility Detect ChatGPT?

2026-09-10

Codility tests are timed and the problems can be hard. So a lot of candidates wonder if Codility can tell when an answer came from ChatGPT.

Here is the straight answer.

Codility does not claim to detect ChatGPT directly. It looks for signals around AI use: copying the task text, retyped code, solutions that match AI output, and on some tests, AI tools running on your device.

Signals Codility ties to AI use

Codility's help center describes several checks.

• Copying the task description. Codility says this "could indicate a candidate's attempt to look up the task or employ AI platforms like ChatGPT."
• Typing Pattern Detection. A signal "designed to identify candidates who may be retyping solutions generated by external AI coding assistants like ChatGPT or Claude."
• Similarity Check. "In short, the submitted solutions are cross-referenced against AI-generated solutions."

Typing Pattern Detection "is on by default but can be turned off per assessment." It runs after you submit, and Codility says the candidate "is entirely unaware that this signal is being collected or evaluated."

Limits Codility admits to

These checks are not treated as proof. Codility says the typing flag "suggests a high likelihood, not certainty, of retyping."

Short answers are skipped too. "Solutions that require less than 10 lines of code are automatically skipped to reduce the potential for false positives."

Some tests also add AI follow-up questions after you submit, with "copy/paste prevention, timeboxing, and keystroke monitoring to discourage AI assistance."

The Codility App changes things

Codility has a newer feature called Device Integrity. It targets "hidden desktop applications that feed candidates AI-generated answers in real time."

When a hiring team turns it on, "the candidate must download and install the Codility App in order to take the assessment." So you will know, because the test will not run in a normal browser. Codility lists the feature as "currently available in Preview."

If your test runs in the browser like usual, this check is not active. For how browser tests track your focus, see does Codility track tab switching.

What this means for you

Most of what Codility flags comes from how you use the test page. Pasting code, copying the prompt, and typing a finished answer in one straight pass are the patterns it describes.

StealthCoder is a desktop app that runs separately from the browser. It reads the problem on your screen and helps you work through it, so you can write the code yourself, in your own order, with your own edits.