Python Backend Developer: Free Skill Evaluation

How Backend Systems Work Programming Concepts Backend Responsibilities Int Float Bool Str List Tuple Set Dict None If Elif Else Match/case For While Break Continue Parameters Return values Keyword arguments Default values *args Kwargs Lambda Scope Dictionary Performance characteristics Mutability Hashing Common use cases Classes Objects Constructors Encapsulation Inheritance Polymorphism Abstraction Composition S — Single Responsibility O — Open/Closed L — Liskov Substitution I — Interface Segregation D — Dependency Inversion Decorators Generators Iterators Context managers Closures Comprehensions Descriptors concepts Magic methods Dataclasses Type hints Optional Union Literal TypedDict concepts Protocol concepts Generics TypeVar Callable typing Custom exceptions Exception hierarchy Exception translation Retryable vs non-retryable errors Files Pathlib JSON CSV Serialization concepts Structured logging Contextual logs Exception logging Correlation IDs Passwords JWT tokens API keys Secrets Unnecessary personal data Object references Garbage collection Reference counting concepts Cycles Memory leaks Large datasets Streaming Memory-efficient processing Concurrency Parallelism Asynchronous I/O Thread Locks Race conditions Thread safety GIL concepts Process Process pool IPC concepts Event loop Coroutine Task Await Gather Timeout Cancellation Semaphore Structured Concurrency Concepts What free-threaded Python means Compatibility concerns Concurrency implications Why normal Python builds and async architectures still remain highly relevant 75 MCQs 50 Coding Tasks Arrays/lists Strings Hash maps Sets Stacks Queues Heaps Trees Graphs fundamentals Sorting Searching Recursion Binary search Sliding window Two pointers Relational model Tables Rows Columns Schema Keys Constraints SELECT INSERT UPDATE DELETE Joins GROUP BY HAVING Subqueries CTE Window functions CASE Transactions Indexes Execution plans Query optimization Schema design Data types Locking Isolation JSONB Connection management Atomicity Consistency Durability Read Committed Repeatable Read Serializable concepts Dirty reads Non-repeatable reads Phantom reads Lost updates B-tree concepts Composite indexes Selectivity Index order Write overhead EXPLAIN EXPLAIN ANALYZE Sequential scans Index scans Join choices Request Response Method Headers Body Cookies Status codes HTTPS/TLS concepts Resources URL design HTTP semantics Statelessness Input Validation Output Errors Authorization Idempotency Rate limits Application Routers Path operations Path parameters Query parameters Request bodies BaseModel Nested objects Validators Custom validation Serialization Settings concepts Database sessions Authentication Tenant resolution Shared validation Response Models Error Handling Fastapi Async Engines Sessions Declarative models Queries Relationships Async SQLAlchemy concepts Migrations Revision Upgrade Downgrade Schema versioning Pool size Max overflow Connection leaks FastAPI PostgreSQL SQLAlchemy Alembic Pagination Filtering Search OpenAPI Tests Django Models QuerySets Select_related Prefetch_related Serializers Views Viewsets Permissions Django Admin APIs Async Microservices AI backends Complete business platforms Admin Mature ORM Integrated authentication Session Basic concepts Token JWT OAuth2 Access tokens Refresh tokens Claims Signatures Expiry Rotation Revocation concepts Rbac Object-Level Authorization Authorization Code PKCE Client Credentials Scopes Resource server concepts Oidc SQL injection Broken authorization CORS CSRF XSS awareness Rate limiting Password hashing Secure cookies Secret management Organization Users Roles Tenant isolation JWT/OAuth concepts Audit Hashes concepts Caching TTL Cache-aside Invalidation Distributed locks concepts Cache Hit Cache Miss Cache Stampede Stale Data Email Reports Exports Image processing AI jobs Worker Broker Result backend Retry Scheduling Queue Design Queue Visibility timeout Dead-letter queue Sns Command Event Topic Partition Producer Consumer Consumer group Offset Ordering Delivery semantics Service boundaries Loose coupling Independent deployment Database ownership Modular Monolith First REST Events Asynchronous workflows Timeouts Retryable errors Exponential backoff Jitter Max attempts Circuit Breaker Local transactions Distributed consistency Saga concepts Compensating operations Redis Kafka concepts Background worker Outbox Delivery Retries Duplicate delivery Upload Download MIME type File limits Documents Images Presigned Urls Chat Real-time updates Notifications Progress AI output SQL search PostgreSQL full-text concepts Elasticsearch/OpenSearch awareness Cursor/Keyset Fixed window Token bucket concepts Fixtures Parametrization Exceptions Markers External APIs Email providers Payment clients Auth Database Database Integration Testing Kafka where relevant Contract Testing Load Stress Spike Soak K6 Locust concepts Throughput P50 P95 P99 Error rate Query time Connection pool N+1 Index Async Performance Large objects Unbounded caches Streaming responses Logs Metrics Traces Structured Logging Requests Latency DB pool Cache hit ratio Queue depth Trace Span Context Alerting Containers Dockerfile Multi-stage build Networking Volumes Environment variables Docker Compose Filesystem Processes Networking basics Pods Deployments Services ConfigMaps Health probes Scaling Rolling deployment Aws Iam Ec2 Rds S3 Aws Lambda Aws Sqs/Sns Step Functions Awareness Alerts Ci/Cd Github Actions Environments Secret Management Rolling Blue/green Canary concepts Repository Service Factory Strategy Adapter Observer Dependency Injection Unit of Work concepts Domain Infrastructure Delivery/API Low-Level Design Requirements Traffic API Cache Storage Reliability Security Observability URL Shortener Payment Backend Booking Platform Notification Service Chat Backend File Processing Platform SaaS Backend Learning Management Backend E-Commerce Backend AI Processing Platform Blocking async External dependency Event loop blocking Downstream dependency Object retention Background workers Large in-memory objects Webhooks Queue redelivery Acknowledgement Requests/sec Error Rate CPU PostgreSQL Connections Slow queries LLM APIs Structured output Tool calls concepts Embeddings Vector search concepts RAG fundamentals Ai Backend Architecture Ai Job Processing Quotas Token tracking Prompt injection awareness Tenant security Output validation Document retrieval Rate limit Usage tracking