~learn.
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❯ arena · learn by playing

Arena.

A daily challenge, weekly leagues and quick games, all built from the course. Every answer you get right here is something you'll get right in an interview.

read the guide →
daily challengeresets 00:00 IST

5 questions.
20 seconds each.

Same five for everyone today, drawn from every quick check and trial in the course. Faster right answers score more.

Play today's challenge →
this weekfull board →
Tallying this week's league…
level–
daily streak–best 0d
this week–local pts · guest
leagueL1Intern3,589 questions in the bank
design of the week · …One open problem a weekA new system design problem every Monday. Submit your design, vote on everyone else's, get featured.open →review queue · spaced repetitionLoading your deck…Missed trial questions, flagged cards and highlights come back right before you forget them.daily standup →written papers · by handSit a week's exam paper with a pencilExplain, estimate and draw the design by hand; every answer is marked against the scheme.all papers →

Arena games

60–90 second rounds. Best scores stay in this browser.

Playground

The Engineering Playground, mapped to the lessons.
how scoring worksLessons +50 · stages +5 · quick checks +3 · daily up to +60 · trials +40 · review +10 · active day +5points table →new to the Arena? XP vs points, leagues and streaks explained →