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
1,033 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
[Go] Mutex Concurrency primitives
qagogoqa - Multiple ChoiceHard
[Go] WaitGroup Concurrency primitives
qagogoqa - Multiple ChoiceHard
[Go] sync.Once Concurrency primitives
qagogoqa - Multiple ChoiceHard
[Go] Cond Concurrency primitives
qagogoqa - Multiple ChoiceHard
[Go] Pool Concurrency primitives
qagogoqa - Multiple ChoiceIntermediate
[GraphQL] __schema Query the schema
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] __typename Query the schema
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Playground Query the schema
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Production Query the schema
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Security Query the schema
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Side effects Write data
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Input types Write data
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Return Write data
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Multiple fields Write data
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Validation Write data
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Exact fields Read data with exact shape
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Over-fetching Read data with exact shape
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Nested Read data with exact shape
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Aliases Read data with exact shape
qagraphqlgraphqlqa - Multiple ChoiceIntermediate
[GraphQL] Fragments Read data with exact shape
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Default Field resolution functions
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Arguments Field resolution functions
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] N+1 problem Field resolution functions
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] DataLoader Field resolution functions
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Async Field resolution functions
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] SDL Type system definition
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Object types Type system definition
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Scalars Type system definition
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Enums Type system definition
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Unions/Interfaces Type system definition
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] WebSocket Real-time events
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Subscribe Real-time events
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] PubSub engine Real-time events
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Filter Real-time events
qagraphqlgraphqlqa - Multiple ChoiceHard
[GraphQL] Auth Real-time events
qagraphqlgraphqlqa - Multiple ChoiceHard
[HTTP API] ETag Reduce server load and latency
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Last-Modified Reduce server load and latency
qahttphttpqa - Multiple ChoiceHard
[HTTP API] no-store Reduce server load and latency
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Max-age Reduce server load and latency
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Vary Reduce server load and latency
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Allow-Origin Cross-Origin Resource Sharing
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Preflight Cross-Origin Resource Sharing
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Credentials Cross-Origin Resource Sharing
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Custom headers Cross-Origin Resource Sharing
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Max age Cross-Origin Resource Sharing
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Idempotent Remove a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Cascade Remove a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 204 Remove a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 405 Remove a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Default Read a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Query params Read a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Idempotent Read a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Safe Read a resource
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Protobuf RPC framework using Protocol Buffers
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Stream types RPC framework using Protocol Buffers
qahttphttpqa - Multiple ChoiceHard
[HTTP API] HTTP/2 RPC framework using Protocol Buffers
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Service def RPC framework using Protocol Buffers
qahttphttpqa - Multiple ChoiceHard
[HTTP API] Deadlines RPC framework using Protocol Buffers
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Content-Type Request/response metadata
qahttphttpqa - Multiple ChoiceIntermediate
[HTTP API] Authorization Request/response metadata
qahttphttpqa
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.