This error is caused by wrong CORS config. To fix it:

• Update swagger by adding :

.addServer('http://localhost:3000')

• Add origin in CORS config (the address you're using) :

app.enableCors({origin: 'http://localhost:3000'});

If you want nestjs to add api/v1 to every endpoint then use setGlobalPrefix('api/v1') to do that.

https://docs.nestjs.com/faq/global-prefix#global-prefix

In most cases the most appropriate way to achieve this is by using setGlobalPrefix method which adds prefix to your API endpoints and URL used by swagger.

const app = await NestFactory.create(AppModule);
app.setGlobalPrefix('querybuilder');

However, if your routing is handled by external server (e.g. nginx), you can add the prefix only to the URL used by swagger using addServer method.

const options = new DocumentBuilder()
  .setTitle('Query Builder - MongoDb Parser')
  .addServer('/querybuilder')