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Motivation

@nestjs/swagger relies on reflect-metadata at runtime, which only exposes basic type signatures. Unions, generics, and literal types are erased. To work around this, you duplicate type information in decorators:

// You already have this type
status: 'pending' | 'shipped' | 'delivered';

// But you also need this decorator to make the spec accurate
@ApiProperty({ enum: ['pending', 'shipped', 'delivered'] })
status: 'pending' | 'shipped' | 'delivered';

When they drift apart, your spec lies about your API.

nestjs-openapi reads your TypeScript source directly using the AST. Your types are your spec—no duplication, no drift.

Quick start

pnpm add -D nestjs-openapi

Create openapi.config.ts:

import { defineConfig } from 'nestjs-openapi';

export default defineConfig({
  output: 'openapi.json',
  files: {
    entry: 'src/app.module.ts',
  },
  openapi: {
    info: { title: 'My API', version: '1.0.0' },
  },
});

Generate:

npx nestjs-openapi generate

Documentation

Full documentation at nestjs-openapi.vercel.app

• Configuration
• Security schemes
• Serving specs at runtime
• Migration from @nestjs/swagger
• CI/CD recipe
• FAQ

Contributing

See CONTRIBUTING.md.

Sponsors

License

MIT