Cairn.

ONE ROUND OR A PRACTICE ROUTINE

Choose your next step.

Review one system design interview, or use a subscription for repeated practice. Compare what each includes before choosing.

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ONE INTERVIEW · A CONCRETE NEXT STEP

System Design · one-round review

A 40-minute Korean AI interview. Evidence from your answers, up to three observed gaps, and one next action.

  • Text and diagram answers
  • Evidence report included
  • Additional AI drills and human review are separate

$39 / one round

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Review the pack · $39

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For repeated practice

Monthly credits for AI interviews, system design and code practice. Subscriptions renew automatically until canceled.

Pro Monthly

Selected

Prepare at your own pace, month by month.

$35billed monthly

900 credits per calendar month (UTC)

  • Fast and detailed AI feedback
  • Original System Design and Code Craft practice
  • Coding and resume preparation tools
  • AI mock interviews using your monthly credits

Pro Annual

A full year of interview preparation.

$179billed annually

900 credits per calendar month (UTC)

  • Fast and detailed AI feedback
  • Original System Design and Code Craft practice
  • Coding and resume preparation tools
  • AI mock interviews using your monthly credits

Review your choice

$35 charged each month. Renews automatically until you cancel online in Billing. Review your final total on the secure Stripe checkout page.

900 credits per calendar month (UTC); unused credits do not roll over. Code review costs 6 credits in Fast mode or 12 in Deep mode. AI mock interviews use credits; review the credit estimate before starting each interview. Refund policy · Terms

How do credits work?

AI requests use credits based on the task and feedback mode. Your monthly allowance is shown above. Credits reset on the first day of each calendar month (UTC), including on annual plans. Unused allowance and bonus credits do not carry over. A free reasoning check uses no credits.

Can I stop at any time?

Cancel renewal online from Billing, without giving a reason. Access continues through the paid period. Contact support to request a refund; your statutory rights remain in place.

Practice feedback is for learning. No plan includes a hiring guarantee or endorsement from an employer.