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
4,318 challenges matching your filters
- Multiple ChoiceIntermediate
REST vs GraphQL
backendintermediate - Multiple ChoiceIntermediate
Monolith vs Microservices
backendintermediate - Multiple ChoiceBeginner
Authentication vs Authorization
backendbeginner - Multiple ChoiceBeginner
Cache Hit vs Miss
backendbeginner - Multiple ChoiceBeginner
SQL SELECT
backendbeginner - Multiple ChoiceBeginner
Primary Key
backendbeginner - Multiple ChoiceIntermediate
Foreign Key
backendintermediate - Multiple ChoiceBeginner
JOIN Types
backendbeginner - Multiple ChoiceIntermediate
LEFT JOIN
backendintermediate - Multiple ChoiceBeginner
GROUP BY
backendbeginner - Multiple ChoiceIntermediate
HAVING vs WHERE
backendintermediate - Multiple ChoiceBeginner
ORDER BY
backendbeginner - Multiple ChoiceIntermediate
Index Purpose
backendintermediate - Multiple ChoiceHard
Index Types
backendhard - Multiple ChoiceIntermediate
Normalization
backendintermediate - Multiple ChoiceHard
1NF, 2NF, 3NF
backendhard - Multiple ChoiceIntermediate
ACID Properties
backendintermediate - Multiple ChoiceIntermediate
Transactions
backendintermediate - Multiple ChoiceBeginner
ROLLBACK
backendbeginner - Multiple ChoiceHard
Isolation Levels
backendhard - Multiple ChoiceIntermediate
Connection Pooling
backendintermediate - Multiple ChoiceIntermediate
N+1 Problem
backendintermediate - Multiple ChoiceIntermediate
Eager vs Lazy Loading
backendintermediate - Multiple ChoiceIntermediate
ORM Purpose
backendintermediate - Multiple ChoiceIntermediate
Prepared Statements
backendintermediate - Multiple ChoiceBeginner
Aggregate Functions
backendbeginner - Multiple ChoiceIntermediate
UNION vs UNION ALL
backendintermediate - Multiple ChoiceIntermediate
EXPLAIN
backendintermediate - Multiple ChoiceIntermediate
Views
backendintermediate - Multiple ChoiceIntermediate
Stored Procedures
backendintermediate - Multiple ChoiceIntermediate
Database Migrations
backendintermediate - Multiple ChoiceIntermediate
CI/CD Pipeline
backendintermediate - Multiple ChoiceIntermediate
Docker Container
backendintermediate - Multiple ChoiceIntermediate
Docker vs VM
backendintermediate - Multiple ChoiceIntermediate
Dockerfile
backendintermediate - Multiple ChoiceIntermediate
Docker Compose
backendintermediate - Multiple ChoiceIntermediate
Kubernetes
backendintermediate - Multiple ChoiceIntermediate
K8s Pod
backendintermediate - Multiple ChoiceIntermediate
K8s Service
backendintermediate - Multiple ChoiceIntermediate
Infrastructure as Code
backendintermediate - Multiple ChoiceHard
GitOps
backendhard - Multiple ChoiceIntermediate
Monitoring Tools
backendintermediate - Multiple ChoiceIntermediate
Rollback Strategy
backendintermediate - Multiple ChoiceHard
Immutable Infrastructure
backendhard - Multiple ChoiceIntermediate
Environment Variables
backendintermediate - Multiple ChoiceIntermediate
Log Aggregation
backendintermediate - Multiple ChoiceIntermediate
Secrets Management
backendintermediate - Multiple ChoiceIntermediate
Horizontal Pod Autoscaling
backendintermediate - Multiple ChoiceHard
Liveness vs Readiness
backendhard - Multiple ChoiceIntermediate
Helm Charts
backendintermediate - Multiple ChoiceHard
ArgoCD
backendhard - Multiple ChoiceIntermediate
Downtime Minimization
backendintermediate - Multiple ChoiceIntermediate
Repository Pattern
backendintermediate - Multiple ChoiceIntermediate
Service Layer
backendintermediate - Multiple ChoiceIntermediate
Dependency Injection
backendintermediate - Multiple ChoiceIntermediate
Factory Pattern
backendintermediate - Multiple ChoiceIntermediate
Observer Pattern
backendintermediate - Multiple ChoiceIntermediate
Strategy Pattern
backendintermediate - Multiple ChoiceIntermediate
Middleware Pattern
backendintermediate - Multiple ChoiceIntermediate
Adapter Pattern
backendintermediate
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.