Play
A few minutes of practice that makes you faster at reading cron. New questions every day, with a streak to keep you honest.
Play on BackendBench: Daily Cron Quiz (five fresh questions every day); Spot the Bug daily puzzle (one real java bug a day, tap the line, keep a streak); Kafka rebalance simulator (range, sticky and cooperative assignment, animated); JPA N+1 visualizer (lazy vs join fetch vs batch size, with the sql); Deadlock and starvation visualizer (lock ordering, trylock and thread-pool starvation); GC and heap visualizer (young, old, promotion and g1 vs zgc pauses); Spring request lifecycle (filters, interceptors, advice and transactions). Each one is free, needs no sign-up and runs entirely in your browser, so nothing you enter is uploaded.