Cla64.ai

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Try the free exercise with no sign-up, or enter the weekly challenge free with an account. Premium exercises come in one-time packs, each valid for one month from the day you buy, or with the monthly plan.

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  • Concert Tickets exercise

    15 minutes, as often as you like. No account needed.

  • The weekly challenge

    One free attempt at each week's challenge, with a free account.

  • Written feedback

    Sign up free to read it after each session.

Concert Tickets

Seat B1held for2 min to payPaidHeldOn sale
A seat is held for 2 minutes while someone pays, then goes back on sale.

Time 15 minLevel easyFree

  • A concert sale sold out, but only a third of the seats were ever paid for.
  • Use the promoter's complaint and the sale's log to find out why the unpaid seats stayed unavailable.
  • Reproduce it with a test, fix it, and keep the test.
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Packs and monthly plan

The premium exercises, at full length, with written feedback. Packs are one-time and last one month from purchase. The monthly plan gives up to 30 interviews each billing month; unused ones don't carry over, and you can cancel any time.

  • 1 interview

    $5 each

    $5

  • 5 interviews

    $3 each, save 40%

    $15

  • Up to 30 interviews

    Every month, cancel any time

    $20/month

Subscriber perk: add 5 more interviews any time for $5 instead of $15.

Prices are in USD, tax included. No extra charges at checkout. Concert Tickets and your weekly-challenge attempt never use a session.

For hiring teams

Use Cla64.ai to interview candidates on real coding exercises, with an AI interviewer and written feedback. For team access, write to contact@cla64.ai.