Does Codility Detect a Second Monitor?

2026-09-25

Plenty of developers work with two screens every day. So when a Codility test link arrives, it is normal to wonder if that extra monitor will get you flagged.

Here is what Codility actually says.

Codility does not say publicly that it can count or detect the monitors plugged into your computer. What it does document is a rule for screen proctoring: if the hiring team turns it on, you are asked to keep only one screen open.

The one monitor rule

Codility's screen capture setting says "When Screen Proctoring is enabled, it will record the candidate's screen."

The same page adds: "The candidate should only have one monitor open if they use multiple screens, as well as the most updated versions of their browsers."

Another help article puts it the same way. Candidates must "keep only 1 screen open (if they have a computer with multiple screens)."

When screen proctoring applies

Screen proctoring is not on by default. Codility says "Proctoring is disabled by default, giving recruiters the flexibility to choose when to enable it on new tests."

When it is on, it comes in two forms:

• Snapshots, where "the candidate's screen is being captured as snapshots at certain intervals"
• Video, where "a full recording of a screen is made"

You will be asked to share. Codility says candidates "can choose between sharing a tab, a window, or entire screen." It also says "We currently only support Chrome for any recording and screenshooting related functionality."

What Codility tracks without screen capture

Even with no screen recording, other signals can be on. Codility says "Proctoring monitors whether candidates navigate away from the Codility browser tab to engage in other activities." More on that in does Codility track tab switching.

Codility's Typing Pattern Detection is also aimed at "the increasingly common practice of using AI tools on secondary devices to bypass assessments." It looks at how code is typed, not at your hardware.

For how another platform handles this, see does HackerRank detect external monitors.

Keeping your setup simple

If your test asks for screen sharing, follow the one screen rule. It is stated plainly, and it is easy to follow.

StealthCoder is an AI overlay that stays invisible during screen share. It runs as a desktop app separate from the browser, reads the problem on your screen, and helps you work through it without a second monitor.