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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1,575 challenges matching your filters
- Code AnalysisIntermediate
Trace: Index Usage
backendanalysisintermediate - Code AnalysisIntermediate
Trace: N+1 Detection
backendanalysisintermediate - Code AnalysisIntermediate
Trace: Pagination Offset
backendanalysisintermediate - Code AnalysisHard
Trace: Lost Update
backendanalysishard - Code AnalysisHard
Trace: Retry Storm
backendanalysishard - Code AnalysisBeginner
Trace: Status Code Choice
backendanalysisbeginner - Code AnalysisIntermediate
GraphQL query shape
backendintermediate - Code AnalysisBeginner
REST pagination response
backendbeginner - Code AnalysisIntermediate
gRPC service definition
backendintermediate - Code AnalysisIntermediate
API Gateway route
backendintermediate - Code AnalysisBeginner
OpenAPI path spec
backendbeginner - Code AnalysisIntermediate
Exponential backoff timing
backendintermediate - Code AnalysisIntermediate
Rate limit header
backendintermediate - Code AnalysisHard
Idempotency key flow
backendhard - Code AnalysisIntermediate
Webhook vs Polling
backendintermediate - Code AnalysisHard
Circuit breaker states
backendhard - Code AnalysisIntermediate
Load balancer algorithm
backendintermediate - Code AnalysisBeginner
Health check response
backendbeginner - Code AnalysisHard
Circuit breaker flow
backendhard - Code AnalysisHard
Service discovery flow
backendhard - Code AnalysisIntermediate
Graceful shutdown steps
backendintermediate - Code AnalysisIntermediate
API Gateway aggregation
backendintermediate - Code AnalysisHard
Saga orchestration
backendhard - Code AnalysisIntermediate
Canary analysis
backendintermediate - Code AnalysisIntermediate
Stateless session
backendintermediate - Code AnalysisIntermediate
JWT decode
backendintermediate - Code AnalysisIntermediate
bcrypt comparison
backendintermediate - Code AnalysisIntermediate
OAuth flow steps
backendintermediate - Code AnalysisIntermediate
RBAC check
backendintermediate - Code AnalysisBeginner
Bearer token in header
backendbeginner - Code AnalysisIntermediate
Session store
backendintermediate - Code AnalysisHard
Refresh token rotation
backendhard - Code AnalysisIntermediate
CORS with credentials
backendintermediate - Code AnalysisIntermediate
CSRF token validation
backendintermediate - Code AnalysisIntermediate
Cache-Aside pattern code
backendintermediate - Code AnalysisBeginner
Redis SET with EX
backendbeginner - Code AnalysisBeginner
Cache-Control header
backendbeginner - Code AnalysisIntermediate
LRU eviction
backendintermediate - Code AnalysisHard
Cache stampede prevention
backendhard - Code AnalysisIntermediate
ETag validation
backendintermediate - Code AnalysisIntermediate
Memoization example
backendintermediate - Code AnalysisIntermediate
CDN cache hit
backendintermediate - Code AnalysisIntermediate
SELECT with JOIN
backendintermediate - Code AnalysisIntermediate
GROUP BY count
backendintermediate - Code AnalysisIntermediate
LEFT JOIN vs INNER
backendintermediate - Code AnalysisIntermediate
Transaction flow
backendintermediate - Code AnalysisIntermediate
Index choice
backendintermediate - Code AnalysisHard
Normalization 2NF
backendhard - Code AnalysisIntermediate
EXPLAIN output
backendintermediate - Code AnalysisIntermediate
Connection pool
backendintermediate - Code AnalysisIntermediate
SQL injection vulnerable
backendintermediate - Code AnalysisIntermediate
Prepared statement
backendintermediate - Code AnalysisIntermediate
NULL handling
backendintermediate - Code AnalysisBeginner
DISTINCT clause
backendbeginner - Code AnalysisIntermediate
Dockerfile instructions
backendintermediate - Code AnalysisIntermediate
K8s Deployment YAML
backendintermediate - Code AnalysisIntermediate
CI pipeline steps
backendintermediate - Code AnalysisIntermediate
Rolling update
backendintermediate - Code AnalysisIntermediate
Environment config
backendintermediate - Code AnalysisIntermediate
Prometheus metric
backendintermediate
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