How to Use Blackbird with Codility
Codility is the coding screen used by banks, consultancies and large engineering teams.
What Codility monitors
- —Copy-and-paste detection in the editor
- —Window focus loss counting
- —A full keystroke and edit timeline replayed to reviewers
- —Similarity checks against known solutions
- —Optional webcam recording
How Blackbird fits in
Codility's report includes a replay of how your code was written. A solution that appears in three large bursts reads very differently from one built incrementally.
Blackbird is a lightweight native Windows overlay drawn at the system compositor level. It is not a browser tab, an Electron window, or a shared surface, so it does not show up in screen recordings, screen-share streams, or active-window checks. It stays on top, accepts clicks without stealing focus, and disappears instantly with a hotkey. Use the overlay to understand the approach, then build the solution the way you normally would.
Practical tips
- +Never paste — Codility highlights pasted blocks in the report.
- +Write a naive version first, then refine it; the replay should look like thinking.
- +Keep the browser focused; the overlay does not steal focus.
- +Add your own comments and variable names.
Frequently asked questions
Does Codility detect the overlay?
No. Codility's signals come from the editor and browser events, not from your desktop.
Will the keystroke replay expose me?
Only if you paste or type a finished answer in one burst. Build it incrementally.
Can I use the auto-typer?
Yes — it emits real keystrokes with human timing, jitter and corrections rather than a paste.
Does webcam recording matter?
Keep your eyes on the screen and behave normally; the camera never sees the overlay.
You are responsible for following the rules of any exam, employer or institution you use Blackbird with. No tool can account for human observation or behavioural review.