Codility proctoring — short answer
Codility is a technical-assessment platform built around timed coding tasks that are scored automatically. It is useful to separate two different things: automated code evaluation (your solution is run against public and hidden tests) and integrity or proctoring review (optional behavioral signals the employer can enable). Automated scoring is almost always part of a Codility test; proctoring is configurable and varies by employer. This guide summarizes Codility's published integrity documentation, explains privacy considerations, and gives a legitimate preparation plan. It does not describe ways to avoid monitoring.
Policy reviewed: 2026-07-19. Codility settings are chosen by the employer and change over time; confirm details with the official links below.
Key Takeaways
- Your Codility score usually comes from automated tests, including hidden cases for edge conditions and performance.
- Proctoring is a separate, optional layer the employer can enable on Screen assessments.
- Codility documents integrity signals such as copy-paste logging, tab switches, timing, and webcam snapshots.
- Codility states that not every signal is evidence of wrongdoing — signals inform a human review.
- The most effective preparation is timed practice with edge-case and complexity discipline.
Automated evaluation vs proctoring review
| Layer | What it does | Usually present? |
|---|---|---|
| Automated code evaluation | Runs your solution against public and hidden tests for correctness and performance | Yes, core to scoring |
| Similarity analysis | Compares submissions for overlap with known or other solutions | Commonly available |
| Proctoring / integrity signals | Optional behavioral monitoring on Screen assessments | Employer's choice |
Hidden tests are why a solution that passes the visible examples can still score poorly: they cover empty inputs, duplicates, large inputs, and performance limits. Understanding this is about writing better code, not about monitoring.
What Codility documents about integrity
Codility publishes its integrity features for employers, and candidates can read them too:
- Proctoring signals on Screen tests can include copy-paste activity logged in the Timeline, tab switches away from the test, unusually fast completion, attempts to copy the task description, and periodic webcam snapshots, with optional screen or video recording (Codility Assessment Integrity Features). Codility states these signals appear in an integrity widget and that not every signal indicates wrongdoing.
- AI follow-up questions can be generated from a submitted take-home solution to check understanding.
- Device integrity for interviews: Codility documents that its interview app checks only for the presence of known cheating tools and does not record the screen, monitor keystrokes, or collect extra personal data (Device Integrity for Interviews).
The purpose of sharing this is transparency: candidates deserve to know how assessments are scored and reviewed.
How Codility compares to HackerRank and CodeSignal
| Platform | Typical emphasis | Where candidates struggle |
|---|---|---|
| Codility | Algorithmic correctness, hidden tests, performance | Missing edge cases or using a slower-than-required approach |
| HackerRank | Broad problem library and employer customization | Platform-specific rules and input parsing under time pressure |
| CodeSignal | Standardized, timed, score-oriented flow | Hidden tests and follow-up explanation |
Candidate privacy and accommodations
Codility acts as a data processor handling information under the employer's instructions (Codility Security and Legal; Codility privacy policy). Candidate terms are published separately (Codility terms for programmers). If proctoring is enabled, you can ask what is recorded and how long it is retained; webcam snapshots, for example, are documented with a retention window. Request accommodations from the employer before the test date.
A legitimate preparation plan
- Practice timed tasks, not only untimed problem sets, so the clock feels normal.
- Write your edge cases before coding: empty inputs, duplicates, negatives, overflow, and boundaries.
- Target the right complexity; confirm your approach scales to large hidden inputs.
- Use the Codility editor style during practice so input/output handling is familiar.
- After each problem, explain your solution aloud so you can defend it in a follow-up.
- Read the employer's instructions carefully, because rules and proctoring vary by test.
See our software engineer interview questions, the coding interview resource, and the Codility platform page.
What to do if you are flagged
An integrity signal is an indicator that a human reviews, not an automatic penalty. If contacted, stay factual, ask what was flagged, preserve your own notes and drafts, and ask the employer about their review and appeals process.
How GhOst can be used responsibly
GhOst is for preparation: timed mock tasks, edge-case and complexity coaching, and explanation practice, plus take-home or open-book work where the employer permits it and authorized accessibility support. It is not a way to avoid Codility's monitoring or to break an assessment's rules. If a test prohibits external help, do not use any assistant during it. Explore AI for online-assessment preparation.
Related guides
Read how online proctoring works, the CodeSignal policy guide, and the HackerRank AI policy guide. See the FAQ and responsible-use terms.
Sources and review date
- Codility — Assessment Integrity Features
- Codility — Device Integrity for Interviews
- Codility — Security and Legal
- Codility — privacy policy
- Codility — terms for programmers
Policy reviewed: 2026-07-19. Verify current Codility behavior with your test instructions and the official pages above.
Frequently Asked Questions
Screen recording is optional and employer-configured. Codility documents that proctoring on Screen assessments can include copy-paste logging, tab switches, timing signals, and periodic webcam snapshots, with optional screen or video recording. Many tests rely on automated scoring without full recording.
Codility runs your solution against public examples and hidden tests that cover edge cases and performance limits. A solution that passes the visible examples can still fail hidden cases, which is why correctness and complexity both matter.
Codility documents integrity signals and similarity analysis, and can generate AI follow-up questions from a take-home submission to check understanding. It states that not every signal is evidence of wrongdoing; signals inform a human review rather than an automatic penalty.
Many candidates find Codility challenging because hidden tests and performance constraints are central to scoring. HackerRank varies more by employer and problem library. The difficulty ultimately depends on the specific test an employer configures.
Use AI for preparation: practice timed tasks, drill edge cases, check complexity, and rehearse explanations. You still need to understand the final code yourself because follow-up interviews and AI follow-up questions test your reasoning.