A Codility test (Codility Screen, formerly CodeCheck) is an online coding assessment that usually runs from 30 minutes to 2 hours. You cannot pause it, and your code is submitted automatically when time runs out. Each task is scored by hidden tests that check correctness and speed on large inputs, and code that does not compile scores zero. Every test gets a plagiarism check, and employers can switch on proctoring with paste and tab tracking, webcam snapshots or screen recording.
Facts from Codility's own pages, checked November 3, 2026. Employers can change settings, so your invitation email wins if it says something different.
| Products | Codility Screen (online test, formerly CodeCheck) and Codility Interview (live, formerly CodeLive) |
|---|---|
| Length | Usually 30 minutes to 2 hours, set by the employer |
| Pausing | Not possible; code is submitted automatically when time runs out |
| Scoring | Hidden tests for correctness and performance, at least 6 per task; time taken does not change the automated score |
| Example test | The visible example does not count toward your score |
| Code that does not compile | Scores 0 |
| Your results | Only if the employer allows it |
| Retakes | Only if the employer reopens the test; the new score replaces the old one |
| Always on | Plagiarism check against 12 million+ past answers and AI-written answers, same-network checks |
| Optional proctoring | Paste, tab-switch and task-copy tracking, webcam snapshots (kept 30 days), screen and video recording |
| Add-ons | Photo ID check, and a required desktop app that looks for hidden cheating tools |
| Built-in AI | Employers can turn on Codility's own assistant, Claude Code or Codex for a task; every prompt is saved |
| Device | Laptop or desktop browser; no phones or tablets |
| Practice | A free 30-minute demo test and 17 free lessons |
Codility tasks are mostly algorithmic coding problems scored by hidden tests, plus live interviews with whiteboards.
Write a function that solves a stated problem. Hidden tests check that it is correct and that it runs fast enough on large inputs.
Tip: Work out the time complexity before you code. A correct but slow answer loses the performance tests.
Hidden correctness tests check cases the visible example does not show.
Tip: List empty input, a single element, negatives, duplicates and the largest allowed size, and check each one.
Codility also has bug-fixing tasks, where you find and fix the mistake in existing code.
Tip: Change as little as possible. A minimal fix is easier to verify.
Codility Interview is a live session with built-in audio and video and two whiteboards.
Tip: Narrate your approach before you write code, and test it on an example out loud.
Each task has at least 6 hidden tests that check correctness and performance on large inputs. The example test you can see does not count, code that does not compile scores 0, and how fast you finish does not change the automated score.
Employers decide whether you see your results. If they reopen a test for you, the new score replaces the old one.
Codility's 30-minute demo test uses the real editor and scoring, so you see how hidden tests and auto-submit work before the real one.
The 17 lessons run from iterations and arrays through time complexity, prefix sums, sorting, stacks and queues to dynamic programming, each with practice tasks.
Performance tests use large inputs. Before you submit, confirm your solution is fast enough for the biggest input the task allows.
Code that does not compile scores 0, and time running out submits whatever is there. Keep a working version saved as you improve it.
Want problems to work through? Codility practice test: 7 sample tasks
Codility runs a plagiarism check on every test, comparing your answer with more than 12 million past answers and with AI-written answers, and checks that you stay on the same network.
Proctoring is off by default, but employers can turn it on: it tracks pastes, tab switches, copying the task text and retyped AI code, and can take webcam snapshots (kept for 30 days) or record your screen and full video. Paid add-ons include a photo ID check and a required desktop app for macOS or Windows that looks for hidden cheating tools.
Employers can turn on Codility's own AI assistant, Claude Code or Codex for a task or interview, and Codility saves every prompt.
Not safe ones. Codility compares every submission with more than 12 million past answers and with AI-written answers. Coding Copilot gives you an approach, complexity notes and code for the task on your screen to work from.
Coding Copilot in the OphyAI desktop app works during live coding interviews: it transcribes the spoken question, reads the task on screen with one hotkey, and shows an approach, complexity notes and working code in a window hidden from screen sharing. It does not hide from a webcam or from proctoring the employer turns on.
Coding Copilot in the OphyAI desktop app reads the task on your screen with Cmd/Ctrl + Shift + A and returns an approach, complexity notes and working code in an overlay that screen sharing and recording leave out. Separately, employers can turn on Codility's own AI assistant, Claude Code or Codex for a task, and Codility saves every prompt.
Every test gets a plagiarism check against millions of past answers and AI-written answers. Employers can add paste and tab tracking, webcam snapshots, screen recording, ID checks and a desktop app that looks for hidden tools. The OphyAI window is hidden from screen sharing and recording, but not from a webcam, a person watching, or the platform's own keystroke, paste and tab tracking.
Compare every platform: Can online assessments detect AI?
Coding Copilot in the OphyAI desktop app reads the coding problem on your screen with one hotkey and returns an approach, complexity notes and working code in your language.
Use OphyAI Coding Copilot in your Codility interview, not just to practice. In a live Codility Interview, press Space or Cmd/Ctrl + Shift + L and it transcribes the question your interviewer asks out loud; press Cmd/Ctrl + Shift + A and it reads the problem on your screen. The approach, complexity notes and working code appear as a card in a floating overlay that your screen share leaves out, on top of a full-screen editor and without taking the keyboard from it. Follow-ups remember the problem, so "now make it faster" updates the same code.
What employers can switch on: paste and tab tracking, webcam snapshots, screen recording, and a required desktop app that looks for hidden tools.
Cmd/Ctrl + Shift + A snaps the problem window, even when other windows cover it, and Cmd/Ctrl + Shift + S lets you drag a box around part of the screen. In a live interview, Space or Cmd/Ctrl + Shift + L transcribes the question the interviewer asks out loud.
Answers show as a card in a floating overlay that macOS and Windows leave out of screen sharing and recording. It stays on top of a full-screen editor or browser and opens without taking the keyboard from your editor.
Each answer card shows how OphyAI read the problem, what to say first, the code with line numbers, a dry run with edge cases, and the Big O. Follow-ups remember the problem, so "now handle duplicates" updates the same code.
Free download. Coding Interview is on the Premium plan ($59 a month, 500 credits) and uses 15 credits per session. See everything it does
Hiding a window from screen share does not hide it from a webcam, a person watching, keystroke and paste history, tab or focus tracking, or proctoring software.
Usually between 30 minutes and 2 hours, set by the employer. You cannot pause, and your code is submitted when time runs out.
By hidden tests for correctness and performance, at least 6 per task. The example test does not count, and code that does not compile scores 0.
Only if the employer allows it.
Only if the employer reopens it, and the new score replaces the old one.
Codility's free 30-minute demo test and its 17 free lessons, which include practice tasks.
Read on November 3, 2026. Codility Screen and Codility Interview is a product of Codility; OphyAI is not affiliated with Codility.
Download OphyAI Desktop and bring Coding Copilot into your next coding interview: it hears the question, reads the problem, and shows the approach and code in an overlay your screen share leaves out.
