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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445 challenges matching your filters
Clear topic filter- Multiple ChoiceIntermediate
Strategy Pattern
backendintermediate - Multiple ChoiceIntermediate
Middleware Pattern
backendintermediate - Multiple ChoiceIntermediate
Adapter Pattern
backendintermediate - Multiple ChoiceIntermediate
Decorator Pattern
backendintermediate - Multiple ChoiceIntermediate
Singleton Pattern
backendintermediate - Multiple ChoiceIntermediate
Facade Pattern
backendintermediate - Multiple ChoiceHard
Chain of Responsibility
backendhard - Multiple ChoiceHard
Event Sourcing
backendhard - Multiple ChoiceHard
CQRS Pattern
backendhard - Multiple ChoiceHard
Clean Architecture
backendhard - Multiple ChoiceHard
DDD Aggregates
backendhard - Multiple ChoiceIntermediate
SOLID Principles
backendintermediate - Multiple ChoiceIntermediate
Layered Architecture
backendintermediate - Code AnalysisIntermediate
Repository interface
backendintermediate - Code AnalysisIntermediate
DI container
backendintermediate - Code AnalysisIntermediate
Middleware flow
backendintermediate - Code AnalysisHard
Event sourcing replay
backendhard - Code AnalysisIntermediate
Adapter example
backendintermediate - Code AnalysisHard
Clean arch dependency rule
backendhard - Code AnalysisHard
Aggregate root
backendhard - Multiple ChoiceIntermediate
Common HTTP methods beyond GET/POST
backendintermediate - Multiple ChoiceIntermediate
Status code 429
backendintermediate - Multiple ChoiceIntermediate
Multipart form data
backendintermediate - Multiple ChoiceHard
Server-Sent Events
backendhard - Multiple ChoiceIntermediate
API authentication methods
backendintermediate - Multiple ChoiceHard
API throttling
backendhard - Multiple ChoiceHard
Hypermedia API advantages
backendhard - Multiple ChoiceIntermediate
Content negotiation (008)
backendintermediate - Multiple ChoiceIntermediate
Conditional requests
backendintermediate - Multiple ChoiceIntermediate
API pagination types
backendintermediate - Multiple ChoiceIntermediate
Batch API design
backendintermediate - Multiple ChoiceIntermediate
API first design
backendintermediate - Multiple ChoiceIntermediate
Status code 409
backendintermediate - Multiple ChoiceBeginner
Payload too large
backendbeginner - Multiple ChoiceBeginner
Mime types
backendbeginner - Multiple ChoiceHard
HTTP/3 (QUIC)
backendhard - Multiple ChoiceIntermediate
CORS preflight
backendintermediate - Multiple ChoiceIntermediate
API deprecation
backendintermediate - Multiple ChoiceHard
SSE vs WebSocket
backendhard - Multiple ChoiceHard
Vary header
backendhard - Multiple ChoiceIntermediate
Database replication types
backendintermediate - Multiple ChoiceIntermediate
PostgreSQL features
backendintermediate - Multiple ChoiceHard
Window functions
backendhard - Multiple ChoiceIntermediate
CTE (WITH clause)
backendintermediate - Multiple ChoiceHard
Database locking
backendhard - Multiple ChoiceHard
Full-text search
backendhard - Multiple ChoiceHard
Materialized views
backendhard - Multiple ChoiceIntermediate
Partitioning
backendintermediate - Multiple ChoiceIntermediate
Database backup types
backendintermediate - Multiple ChoiceBeginner
Connection string
backendbeginner - Multiple ChoiceHard
Query plan analysis
backendhard - Multiple ChoiceBeginner
Data integrity constraints
backendbeginner - Multiple ChoiceIntermediate
Soft deletes
backendintermediate - Multiple ChoiceIntermediate
UUID vs Auto-increment
backendintermediate - Multiple ChoiceIntermediate
Connection pool sizing
backendintermediate - Multiple ChoiceHard
OAuth implicit flow
backendhard - Multiple ChoiceIntermediate
SAML
backendintermediate - Multiple ChoiceHard
HMAC
backendhard - Multiple ChoiceIntermediate
SQL injection types
backendintermediate - Multiple ChoiceHard
XXE attack
backendhard
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