Why Code Drills exists

Small, self-contained problems are a gym for thinking: you trace what code does, handle every edge case, and pick a sensible way to store data.

Predicting what code does, spotting off-by-one mistakes, choosing a lookup table over a loop, and knowing what grows slowly or quickly are used in debugging, code review and keeping systems fast.

Companies and institutions rarely have the time, skill or interest to evaluate each person in depth. They need a cheap, standard number, so they use proxies: timed puzzles, algorithm quizzes, certificates, keyword filters. These drills are one of those proxies. It is a narrow, imperfect measure and often far from the actual job, but it is common enough that it is worth being ready for.

Learn the patterns well enough to get through, and do not mistake the result for your worth or your real ability. The two are different things.

No sign-up, no paywall, no ads. Open it, swipe, try one, keep going.

Scroll, press the down arrow, or tap Next.

A short panel opens that explains what the question is for and where the skill shows up in real work. It never gives the answer, and closing it leaves your work exactly as it was.

The C#, JavaScript and Python pills at the top show only the questions that exist in that language.

The Notes button on each card opens a box for anything you want to remember about that question. Notes save automatically in this browser, and the checklist can show only the questions that have one.

Completed or Attempted. The checklist counts them per topic.

One tap copies the question, your answer and the verified reference answer, so any AI can grade you against something known to be correct. Progress and notes are saved in your browser only.