Learning PageCategoriesAuthAPIsCachingReliabilityQueuesScalingDatabases Learning PageBrowse Backend Study Games by backend engineering concept area.Learning categories/categories/
Learning categories
Use categories to choose a backend skill path, then jump into a short playable scenario.
Auth
1 game(s) in this concept area.
Auth Intermediate
Inspect authentication scenarios and choose safe backend decisions for tokens, scopes, sessions, CSRF, and object-level authorization.
- Time
- 6-9 minutes
- Concept
- Authentication, authorization, sessions, and token safety
- Foundations
- Auth
- JWT
- sessions
Play Auth Token Inspector APIs
4 game(s) in this concept area.
APIs Beginner
Design REST-style methods and routes for product requirements such as creating users, updating email, searching products, and nested comments.
- Time
- 6-9 minutes
- Concept
- REST API route design
- Foundations
- REST
- API design
- routes
Play API Route Builder APIs Intermediate
Guide browser API requests through CORS decisions covering origins, preflight, credentials, exposed headers, and cache safety.
- Time
- 6-9 minutes
- Concept
- CORS, browser security boundaries, and preflight response design
- Foundations
- CORS
- HTTP
- browser security
Play CORS Preflight Pilot APIs Beginner
Choose the correct HTTP status code for realistic backend scenarios and learn the response semantics behind each answer.
- Time
- 5-8 minutes
- Concept
- HTTP status codes and response semantics
- Foundations
- HTTP
- REST
- status codes
Play HTTP Status Defender APIs Intermediate
Investigate webhook requests and choose safe handling for signatures, replay windows, retries, idempotency, and durable acknowledgement.
- Time
- 6-9 minutes
- Concept
- Webhook verification, replay protection, idempotency, and retry-safe processing
- Foundations
- webhooks
- HMAC
- idempotency
Play Webhook Signature Forensics Caching
1 game(s) in this concept area.
Caching Beginner
Predict cache hits and misses as requests flow through an LRU cache, then experiment with TTL behavior and stale data tradeoffs.
- Time
- 5-8 minutes
- Concept
- Cache hits, misses, LRU, TTL, and stale data
- Data & Performance
- cache
- LRU
- TTL
Play Cache Eviction Lab Reliability
3 game(s) in this concept area.
Reliability Intermediate
Diagnose dependency failures and choose circuit breaker, timeout, fallback, retry, half-open, and bulkhead strategies that reduce blast radius.
- Time
- 6-9 minutes
- Concept
- Circuit breakers, timeouts, retries, fallbacks, and dependency isolation
- Production Reliability
- resilience
- circuit breaker
- timeouts
Play Circuit Breaker Clinic Reliability Intermediate
Diagnose retry scenarios and choose safe idempotency behavior for payments, emails, imports, orders, PUT updates, and scarce inventory.
- Time
- 6-9 minutes
- Concept
- Idempotency, retries, duplicate prevention, and consistency
- Production Reliability
- Idempotency
- Reliability
- Consistency
Play Idempotency Key Clinic Reliability Intermediate
Triage production incidents by choosing useful metrics, logs, traces, queue signals, database evidence, request ids, and alerting strategies.
- Time
- 6-9 minutes
- Concept
- Production observability, incident triage, metrics, logs, traces, and alerts
- Production Reliability
- observability
- incidents
- metrics
Play Observability Incident Triage Queues
1 game(s) in this concept area.
Queues Intermediate
Tune workers, retries, and dead-letter behavior while jobs move through an async queue with failures and poison messages.
- Time
- 7-11 minutes
- Concept
- Async jobs, retries, visibility timeout, and dead-letter queues
- Production Reliability
- queues
- retries
- dead-letter queue
Play Message Queue Simulator Scaling
2 game(s) in this concept area.
Scaling Intermediate
Route simulated traffic across backend servers using round robin, weighted round robin, least connections, and random strategies.
- Time
- 6-10 minutes
- Concept
- Load balancing strategies
- Production Reliability
- load balancing
- scaling
- latency
Play Load Balancer Challenge Scaling Intermediate
Choose rate limiting designs for realistic backend traffic patterns, from public APIs and login endpoints to queues, webhooks, and retry storms.
- Time
- 6-9 minutes
- Concept
- Rate limiting, fairness, backpressure, and abuse protection
- Data & Performance
- Rate limiting
- Scaling
- 429
Play Rate Limit Architect Databases
3 game(s) in this concept area.
Databases Advanced
Defend database invariants from concurrent requests by choosing transactions, locks, constraints, snapshot reads, and optimistic concurrency.
- Time
- 7-10 minutes
- Concept
- Database transactions, isolation anomalies, locks, and invariant protection
- Data & Performance
- SQL
- transactions
- isolation
Play Transaction Isolation Arena Databases Intermediate
Choose the best database index for simplified schemas and queries while learning full scans, covering indexes, sort avoidance, and composite order.
- Time
- 7-10 minutes
- Concept
- Database indexing and query performance
- Data & Performance
- SQL
- indexes
- performance
Play SQL Index Quest Databases Intermediate
Choose safe zero-downtime database migration steps for expanding schemas, backfilling data, rolling out indexes, enforcing constraints, and recovering from failures.
- Time
- 6-9 minutes
- Concept
- Zero-downtime schema migration planning and expand-contract releases
- Data & Performance
- migrations
- schema design
- backfill
Play Schema Migration Runbook