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.
Filter by type
Filter by difficulty
Popular topics
10 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
Local-first software trade-offs
local-firsttrade-offsconsistency - Multiple ChoiceHard
Avoiding Dual-Write Problems
dual-writeconsistencyanti-pattern - Multiple ChoiceHard
Quorum read/write overlap
system-designconsistencyquorum - Multiple ChoiceHard
Lost update race
system-designconcurrencyconsistency - Multiple ChoiceHard
Quorum without read repair
system-designquorumconsistency - Multiple ChoiceHard
Distributed rate limiting consistency
rate-limitingdistributedconsistency - Multiple ChoiceHard
Dual-write migration correctness
migrationdual-writeconsistency - Code AnalysisHard
Quorum read after failed write
system-designquorumconsistency - Multiple ChoiceHard
Consistency boundary choice
architecturedddconsistency - Code AnalysisHard
Aggregate invariants vs eventual consistency
architecturedddconsistency
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.