Next month it will be a year since a guy from my old study group had his CodeSignal results invalidated. I still remember the exact wording, because the recruiter email he forwarded me was one sentence long: "Your assessment results have been invalidated." No reason given, no details, nothing.
He texted it to me at almost 11 PM on a normal weeknight, while I was half done brushing my teeth. I called him right back with toothpaste still in my mouth. He picked up from his car outside the gym, and he wasn't even mad about it, he was just confused, he kept repeating that the test had gone great.
Back then we were both interviewing everywhere, and he was further along than me. He had run a Chrome extension through his entire CodeSignal, the kind that reads the problem and feeds you the answer, and he was sure the whole thing went great. His first two problems took fifteen minutes each, the third one was supposed to be the hardest and he finished it in three minutes. Neither of us thought the three minutes meant anything at the time.
All that caused me to be a bit paranoid, because my own CodeSignal was coming up in two weeks. He thought he had done everything right, and if he could get caught, then I had no idea what these tests could actually see.
But no matter how smooth the test felt from his side of the screen, he had missed one thing. An essential one. He wasn't "paranoid" enough to watch what his own screen recording looked like with the extension running. To be fair, it had never occurred to me either that you could just do that.
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Try InterviewMan FreeA former coworker of mine runs CodeSignal hiring at his company, so a few days later I showed up at his apartment with a list of questions. He opened the dashboard on his laptop and pulled up a real candidate's submission, with me sitting next to him asking dumb questions the whole time.
Every single submission gets a Suspicion Score, it was sitting right next to the code on every row of his queue. He told me most managers check that flag before they even look at what you wrote. They care way more about how your code shows up than what it actually does, in his words.
The biggest factor in that score is the edit history. A real person tries something, deletes half of it, starts over. When optimized code shows up fully formed, with none of that struggle in the history, the score goes nuts.
Then he clicked the webcam tab. 35 percent of the tests that got flagged in 2025 were people looking off screen over and over, that was the number he quoted me anyway.
Paste events show up in the activity log too. Typing speed gets compared against how hard the problem is supposed to be. A solve time that doesn't match the difficulty sticks out the same way, which is the exact gap my friend never thought about. And code that comes out looking like another candidate's code gets its own flag.
He also walked me through what my own test would have waiting for me. AI Proctoring records video and audio and your entire display. You show a government ID before you start. The questions rotate now, so studying leaked answers barely helps anymore.
I remember getting more depressed with every tab he opened.
But then he said the thing I actually came for, and he was literally pointing at his screen when he said it. CodeSignal records your screen and your webcam, and that is where it ends. No process scanning on your machine. No system level audits. Nothing outside the browser window and the video feed.
If something runs on your computer but never shows up in what gets recorded, and never touches the browser tab, then as far as CodeSignal is concerned it does not exist.
That is where my friend lost. His Chrome extension had injected itself into the assessment page. The recording caught it before the Suspicion Score ever came into play. It was just sitting there in the frames, visible to anyone who bothered to look.
His submission, the one he was so sure about... three solved problems, and none of it counted anymore.
I went looking into what other people were using. Reddit threads kept mentioning Cluely, one hundred forty nine ninety nine with the stealth plan, and Interview Coder at two ninety nine, and both of them have overlay windows that show up in screen recordings. If your tool is visible in the recording, you are done before any algorithm even runs.
Armed with all this information, I sat my own CodeSignal two weeks after his results got thrown out, and I ran InterviewMan through the whole thing. Full disclosure: I work on it now. We charge twelve bucks a month on annual, and it is a desktop app, it never touches the browser.
My story turned out ok, eventually. The Suspicion Score came back clean, and the screen recording had nothing in it. I know because I pulled up my own footage afterwards and went through it frame by frame at my coworker's place, since I wanted him to watch too. Not in a single frame.
The score stayed clean because I typed every line myself, read the overlay hints, wrote the code my way. The edit history looked like a real person working through a problem: deletions, partial attempts, corrections, backtracking. The normal mess the score expects from a human.
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Try InterviewMan Free57,000 people use it now, with 4.8 stars from 257 reviews. I searched reddit and discord for anyone who got caught using InterviewMan on CodeSignal and found nothing. All the stealth features are in the twelve bucks, with no one hundred thirty dollar upgrade the way Cluely charges, and no ninety minute session cap the way LockedIn has at one hundred nineteen ninety nine.
It was a stressful, unpleasant couple of weeks, that gave me a few grey hairs of my own. It would have been a shame if I didn't learn anything out of it, right?
Never sit a CodeSignal with a tool you haven't recorded first: not a Chrome extension, not a browser overlay, not anything that touches the page, nothing. Record your own screen in a practice session and actually watch the footage back. If you can see your tool, the hiring team can see it too. You can never be too careful. You never know who is going to press play on the footage.
And type your own code. Let the edit history show the backtracking, the wrong turns, the whole messy process of a human under pressure. The Suspicion Score watches the process just as much as the final answer.
I never found out what happened with his application at that company.
After the invalidation he stopped bringing the whole thing up, he didn't want to talk about it, he didn't care anymore. He was just furious with himself for trusting an extension to stay invisible when he never once watched his own footage. He should have known better.
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