What is the @nestjs/swagger module?

The @nestjs/swagger module automatically generates interactive Swagger/OpenAPI documentation for your NestJS REST API. Setup in main.ts: create a DocumentBuilder config, then SwaggerModule.setup('api', app, document). It reads TypeScript types, DTOs decorated with class-validator decorators, and additional decorators like @ApiProperty(), @ApiOperation(), @ApiResponse(), and @ApiBearerAuth(). DTO properties with class-validator decorators are automatically reflected in the schema. This eliminates the need to manually maintain API documentation. The generated UI at /api is interactive — you can test endpoints directly in the browser. The OpenAPI spec can also be exported as JSON for use with other tools.