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
253 challenges matching your filters
Clear topic filter- 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 ChoiceBeginner
[HTTP API] Behavior Create a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Idempotent? Create a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Upload Create a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Status 201 Create a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] Location Create a resource
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 200 Server response categories
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 201 Server response categories
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 404 Server response categories
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 500 range Server response categories
qahttphttpqa - Multiple ChoiceBeginner
[HTTP API] 301 vs 302 Server response categories
qahttphttpqa - Multiple ChoiceBeginner
[JavaScript] Counter Function retains outer scope after return
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Loop capture Function retains outer scope after return
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] IIFE module Function retains outer scope after return
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Partial Function retains outer scope after return
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Module pattern Function retains outer scope after return
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Object Unpack values from objects/arrays
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Array Unpack values from objects/arrays
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Defaults Unpack values from objects/arrays
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Rest Unpack values from objects/arrays
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Nested Unpack values from objects/arrays
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] var Declarations move to top before execution
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] let TDZ Declarations move to top before execution
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Function decl Declarations move to top before execution
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Expression Declarations move to top before execution
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Class Declarations move to top before execution
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Array merge Expand iterables into elements
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Object merge Expand iterables into elements
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Args Expand iterables into elements
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] Shallow copy Expand iterables into elements
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[JavaScript] String Expand iterables into elements
qajavascriptjavascriptqa - Multiple ChoiceBeginner
[Kubernetes] Key-value Non-sensitive configuration
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Env var Non-sensitive configuration
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Volume mount Non-sensitive configuration
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Update propagation Non-sensitive configuration
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Immutable Non-sensitive configuration
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Shared resources Smallest deployable unit
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] IP address Smallest deployable unit
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Restart policy Smallest deployable unit
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Sidecar pattern Smallest deployable unit
qak8sk8sqa - Multiple ChoiceBeginner
[Kubernetes] Init containers Smallest deployable unit
qak8sk8sqa - Multiple ChoiceBeginner
[Linux] chmod rwx and ownership
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] chown rwx and ownership
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] umask rwx and ownership
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] SUID rwx and ownership
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] Sticky bit rwx and ownership
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] | Chain commands
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] 2>&1 Chain commands
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] /dev/null Chain commands
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] tee Chain commands
qalinuxlinuxqa - Multiple ChoiceBeginner
[Linux] xargs Chain commands
qalinuxlinuxqa - Multiple ChoiceBeginner
[MongoDB] Schema flexibility Flexible JSON-like records
qamongodbmongodbqa - Multiple ChoiceBeginner
[MongoDB] BSON Flexible JSON-like records
qamongodbmongodbqa - Multiple ChoiceBeginner
[MongoDB] _id field Flexible JSON-like records
qamongodbmongodbqa - Multiple ChoiceBeginner
[MongoDB] 16MB limit Flexible JSON-like records
qamongodbmongodbqa - Multiple ChoiceBeginner
[MongoDB] Embedding vs referencing Flexible JSON-like records
qamongodbmongodbqa - Multiple ChoiceBeginner
[Networking] Resolution Domain Name System
qanetworkingnetworkingqa - Multiple ChoiceBeginner
[Networking] Root servers Domain Name System
qanetworkingnetworkingqa
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.