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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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153 challenges matching your filters
Clear topic filter- Code AnalysisIntermediate
Backpressure ignored
architectureresiliencebackpressure - Code AnalysisBeginner
Command/query separation violation
architecturecqrsprinciples - Code AnalysisBeginner
ISP in a module interface
architecturesolidisp - Code AnalysisIntermediate
Event sourcing projection replay bug
architectureevent-sourcingprojections - Code AnalysisBeginner
CQRS lag breaks read-your-writes
architecturecqrseventual-consistency - Code AnalysisHard
Thundering herd on expiry
architectureresiliencecaching - Code AnalysisBeginner
Anemic model with validation elsewhere
architecturedddanemic-model - Code AnalysisIntermediate
LSP: widening (not narrowing) can also break
architecturesolidlsp - Code AnalysisBeginner
Dependency inversion missing in service
architecturesoliddip - Code AnalysisIntermediate
Contract regression: additive vs breaking
architectureapiversioningbackward-compatibility - Code AnalysisBeginner
Choreography observability gap
architectureedasaga - Code AnalysisIntermediate
Orchestration single point
architecturesagaresilience - Code AnalysisBeginner
Shared module creates cycle at package level
architecturemodularitydependencies - Code AnalysisIntermediate
Abstractness/instability zone check
architecturemetricscoupling - Code AnalysisBeginner
Bulkhead absence cascades
architectureresiliencebulkhead - Code AnalysisHard
Idempotency: naive dedupe key
architectureidempotencyconcurrency - Code AnalysisBeginner
Test double misuse
architecturetestingtest-doubles - Code AnalysisIntermediate
Test seam for legacy code
architecturetestingseams - Code AnalysisBeginner
Branch by abstraction setup
architecturerefactoringbranch-by-abstraction - Code AnalysisHard
Aggregate invariants vs eventual consistency
architecturedddconsistency - Code AnalysisBeginner
Value object mutability bug
architecturedddvalue-object - Code AnalysisHard
Anti-corruption layer absence
architecturedddacl - Code AnalysisBeginner
Modular monolith boundary enforcement
architecturemodularitymonolith - Code AnalysisHard
Feature flag interaction bug
architecturefeature-flagstesting - Code AnalysisBeginner
Query side should not be reused for writes
architecturecqrsseparation - Code AnalysisHard
Gateway timeout as circuit breaker signal
architectureresiliencecircuit-breaker - Code AnalysisBeginner
Anemic DTO vs domain object
architecturedddanemic-model - Code AnalysisHard
Repository per aggregate only
architecturedddrepository - Code AnalysisBeginner
Strangler deletion debt
architecturemigrationstrangler-fig - Code AnalysisHard
Event schema evolution break
architectureedaversioning - Code AnalysisBeginner
Dependency injection container misuse
architecturedicoupling - Code AnalysisHard
Saga pivot vs compensation ordering
architecturesagadistributed - Code AnalysisBeginner
Cyclic dependency via event handler
architecturemodularityeda
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