ScriptAssist NestJS API
Senior-level NestJS coding challenge — refactored a task management API with intentional architectural flaws into a production-grade system with caching, queues, security, and observability.
TypeScriptNestJSPostgreSQLTypeORMBullMQRedisJWTBun
About
TaskFlow API was a senior backend engineer coding challenge that presented a codebase full of intentional anti-patterns, security vulnerabilities, and scalability bottlenecks to fix.
Tech Stack
- NestJS + TypeScript
- TypeORM with PostgreSQL
- BullMQ with Redis for async task queue processing
- Bun as the package manager and test runner
What Was Fixed / Implemented
- Performance — proper DB query strategies with joins, eager loading, bulk operations, and query indexing
- Architecture — domain separation, service abstractions, consistent transaction management, SOLID principles, and CQRS pattern
- Security — refresh token rotation, multi-level authorization checks, secure rate limiting, input validation and sanitization
- Resilience & Observability — comprehensive error handling, contextual logging, meaningful health checks, and observability patterns
Advanced Areas
- Distributed systems design considerations
- System reliability under concurrent load
- Performance benchmarking