System design problems specific to mobile apps — offline-first sync, battery, location, push notifications, and platform constraints on iOS and Android.
3 min read “Design Family Sharing” is a multi-account mobile-system-design question — the interviewer is checking whether you understand identity and authorization across […] Read article
2 min read Plant care apps (PictureThis, Planta, Greg) and pet care apps (11pets, Pawtrack) seem niche but pop up frequently in mobile Read article
2 min read Read-it-later apps (Pocket, Instapaper, Matter, Readwise Reader) save articles for later consumption — stripped of ads, formatted for reading, available Read article
2 min read Group expense apps (Splitwise, Tricount, SettleUp) sit at the intersection of social and financial. The interview tests whether you understand Read article
2 min read Restaurant reservation apps (OpenTable, Resy, Tock) are surprisingly rich system design topics. Inventory management at sub-hour granularity, time-zone awareness, no-show Read article
2 min read Smart lock apps (August, Schlage, Yale, Latch, Airbnb) combine mobile, IoT, and security in a high-stakes UX. Forget your password? Read article
2 min read Mobile remote controller apps (Apple TV Remote, Sonos, Logitech Harmony, smart-home remotes) are tiny apps with surprising depth. Real-time low-latency Read article
2 min read Receipt-scanning expense apps (Expensify, Zoho Expense, modern fintech wallets) have become routine for business travelers and freelancers. The interview tests Read article
2 min read Mobile sleep tracking has gone from gimmick to mainstream — Apple Health, Fitbit, Oura Ring, Whoop, and dozens of dedicated Read article
2 min read Investment-tracking apps (Personal Capital, Wealthfront, Empower, Yodlee-based apps) aggregate accounts across brokerages, banks, and retirement plans. The interview is multidisciplinary: Read article
2 min read Habit-tracking apps (Streaks, Productive, Habitify, Atomic Habits-inspired apps) are simple-looking but reveal interesting system design questions: streak calculation, time-zone sensitivity, Read article
2 min read Travel itinerary apps (TripIt, Hopper, Google Trips legacy) auto-organize a trip from confirmation emails into a unified itinerary. The interview Read article
2 min read Personalized push notifications are an entire engineering discipline. The wrong notification produces uninstalls; the right one produces engagement. Companies like Read article
3 min read Deep linking — the ability to open a specific screen in your app from a URL — is fundamental to Read article
2 min read Mobile loyalty apps (Starbucks, Chipotle, Dunkin) are unusually rich mobile system design topics. They combine payment processing, loyalty points, mobile Read article
