# Nestjs Clean Typescript > Clean NestJS API development with TypeScript following SOLID principles, modular architecture, and comprehensive testing practices. Use when this capability is needed. - Skill: `tomevault-io/nestjs-clean-typescript` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/nestjs-clean-typescript` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/nestjs-clean-typescript/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/nestjs-clean-typescript --- # NestJS Clean TypeScript Guidelines by Alberto Basalo for developing clean NestJS APIs using TypeScript. These rules emphasize strong typing, clean code principles, and architectural best practices. ## TypeScript General Principles - Always declare the type of each variable and function (parameters and return value) - Avoid using any; create necessary types instead - Use JSDoc for public classes and methods - One export per file ## Naming Conventions - PascalCase for classes - camelCase for variables and functions - kebab-case for files and directories - UPPERCASE for environment variables - Boolean variables use prefixes: isX, hasX, canX ## Function Design - Write short functions with a single purpose. Less than 20 instructions - Use early returns to avoid nesting - Apply RO-RO pattern: pass objects for multiple parameters, return objects for results ## Data and Classes - Prefer immutability for data with readonly and as const - Follow SOLID principles - Classes should have: - Less than 200 instructions - Fewer than 10 public methods - Fewer than 10 properties ## NestJS Specific Guidelines - Use modular architecture with one module per domain/route - Use MikroORM entities for persistence - One service per entity - DTOs validated with class-validator - Global filters, middlewares, guards, and interceptors in core module ## Testing - Use Jest framework - Follow Arrange-Act-Assert convention - Write unit tests for each public function - Include end-to-end tests per API module --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/mindrally) — claim your Tome and manage your conversions.