Quarry vs Sine

Quarry is a focused, offline gym for data and coding interviews. 108 hand-picked problems across SQL, pandas, and Python — write real code, run it on your device, and get graded instantly. Everything runs on-device. The SQL and Python engines are built into the app, so there's no sign-up, no internet requirement, and nothing you write ever leaves your phone or iPad. Practice on a plane, on the subway, or anywhere. WHAT'S INSIDE • 108 problems across three tracks: SQL queries, pandas data wrangling, and Python algorithms & data structures. • Real execution, real grading. Your output is checked against the expected result — no self-marking. • Company tags. Filter problems by the company you're interviewing at. • Hints and full solutions when you're stuck. • Difficulty levels from Easy to Hard, grouped by topic. • A free-form Playground for scratch SQL and Python. • Universal app — designed for both iPhone and iPad. PRIVATE BY DESIGN No accounts. No analytics. No ads. No tracking. Quarry collects nothing and works fully offline. Whether you're prepping for a data analyst, data engineer, data scientist, or software role, Quarry gives you a quiet, fast place to actually practice.

Most people are told perfect pitch is you are born with. It is not. It is a skill, and like any skill it comes from short, honest practice. Sine is that practice, made pleasant enough that you keep coming back. HEAR IT. NAME IT. KNOW IT. A note plays. You pick the key. There is no reference note and nothing to compare against, so every answer has to come from your own ear. Between questions a wash of sound clears the last note away, which is the part every other trainer skips. ONE NOTE AT A TIME You start with two notes that sit far apart, then add one more, then one more. The white keys, then the black keys, then the chords that carry most songs. Every level is short, and you pass it when you are ready, not on a schedule. A COACH WHO SAYS LITTLE Sine is a ring-tailed lemur who listens with you. It notices a run of five, a note that used to slip, a slow answer that was still right. It never scolds. Your streak forgives a missed day, because life has those. INTERACTIVE GAMES FOR YOUR EAR Sine Duel races you to a note, or races a friend across the same phone. Defuse plays a run of notes and you tap it back before the fuse burns down. Tune-up plays a note a few hertz off and asks flat, sharp, or in tune. We add more and more games to our library weekly! EVERY ANSWER, KEPT Stats by note and by chord, the note you confuse each one with, and a shelf of badges for what you have done. ENCORE We have a generous free-tier, but if you'd like to support our growing team, Encore unlocks everything now and later. Monthly at $1.99, or yearly at $29.99 with the first 7 days free. Prices vary by country. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period, and can be managed in your App Store account settings. Terms of use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy policy: https://learnsine.com/privacy