LeetCode vs Don't Break Prod

One LeetCode a day keeps your reasoning in play. Introducing LeetCode for iOS and iPadOS. Enjoy LeetCoding right at your fingertips — jump in for quick practice, browse your collections, and stay on top of important events and progress. With LeetCode in the palm of your hand, you can easily: • Search and discover the latest company questions. • View and quickly practice your favorite challenges right in the palm of your hand. • Manage your lists or add to your wishlist to practice later. • Keep track of your personal progress with a rich profile view and widgets. • Stay notified and keep your streak alive — level up with new challenges and quests every day. • Register for contests and sync them to your calendar. Live Activities keep you updated on contest progress — so you never miss a moment. • And more content and features coming every month… Terms of Services: https://leetcode.com/terms/ Privacy Policy: https://leetcode.com/privacy/

Don't Break Prod turns system design practice into a daily habit. Every day brings one timed incident: a production system is failing, the clock is running, and you make the calls to bring it back. Diagnose the root cause, mitigate, recover, and harden before the timer hits zero. It is built for engineers preparing for system design and on-call interviews, and for anyone who wants to think more clearly about how real systems break. THE DAILY INCIDENT A new production failure every day, the same one for everyone. A cache that went cold, a queue that will not drain, a cert that expired at midnight, a cache key that leaked one tenant's data into another. Time is short, wrong moves cost you seconds, and your score is the time you have left. One scored run per day. Share your result as a spoiler-free card and compare calls with your team. PRACTICE THAT STICKS Work through core topics at your own pace: caching, load balancing, message queues, databases, sharding, consistency, rate limiting, CDNs, and full design walkthroughs like URL shorteners, chat, and news feeds. Spaced repetition brings back what you are about to forget, right when you need it. THREE WAYS TO ANSWER Multiple choice, fill in the blank, and drag-to-order questions, each written to test whether you understand the tradeoff, not whether you can recognize a term. KEEP YOUR STREAK Show up daily and build a streak of days without breaking prod. Earn failover freezes that quietly cover a missed day. Your whole history lives in Profile as a day-by-day grid: every incident survived, every failover spent, every day the pager won. Compare your all-time score with other players on the Game Center leaderboard. PRIVATE BY DESIGN No account, no sign-up, no tracking, no ads. Everything you do stays on your device. The leaderboard is optional and runs on Apple's Game Center. Every question is original writing. The concepts are standard system design material, explained plainly, so you leave understanding the why, not just the answer.