Challenge Library
Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
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12 challenges matching your filters
Clear topic filter- Multiple ChoiceIntermediate
Availability math
system-designavailability - Multiple ChoiceIntermediate
Circuit breaker states
system-designavailabilitycircuit-breaker - Multiple ChoiceHard
Bulkhead isolation
system-designavailabilitybulkhead - Multiple ChoiceIntermediate
Split-brain
system-designconsensusavailability - Multiple ChoiceIntermediate
Exponential backoff with jitter
system-designavailabilityretry - Multiple ChoiceHard
Retry amplification
system-designavailabilityretry - Multiple ChoiceBeginner
Failover active-passive vs active-active
system-designavailabilityfailover - Multiple ChoiceBeginner
Nines and downtime budget
system-designavailabilitynines - Multiple ChoiceBeginner
Multi-region active-active vs active-passive
multi-regionavailabilitytopology - Code AnalysisIntermediate
Retry storm without backoff
system-designavailabilityretry - Code AnalysisHard
Split-brain from naive failover
system-designconsensusavailability - Code AnalysisBeginner
No timeout on downstream call
system-designavailabilityresilience
Practice now, dominate the arena
Every challenge here is drawn from the live Code Royale pool. Review a question, then head to the arena to answer under pressure against a real opponent — 3-minute matches, Elo ranking, and badge tiers on the line.