API Reference for NestJS

Installation#

npm install @scalar/nestjs-api-reference

Usage#

Set up NestJS and set up NestJS Swagger and pass an OpenAPI/Swagger document to the apiReference middleware:

import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger'
import { apiReference } from '@scalar/nestjs-api-reference'
 
/* ... */
const app = await NestFactory.create(AppModule)
 
const config = new DocumentBuilder()
  .setTitle('Cats example')
  .setDescription('The cats API description')
  .setVersion('1.0')
  .addTag('cats')
  .build()
 
const document = SwaggerModule.createDocument(app, config)
/* ... */
 
const OpenApiSpecification =
  /* … */
 
  app.use(
    '/reference',
    apiReference({
      content: document,
    }),
  )

Recommended: If you're serving an OpenAPI/Swagger file already, you can pass a URL, too:

import { apiReference } from '@scalar/nestjs-api-reference'
 
app.use(
  '/reference',
  apiReference({
    url: '/openapi.json',
  }),
)

Using with Fastify Adapter#

When using NestJS with the Fastify adapter instead of Express, you need to set the withFastify option to true:

/* ... */
 
app.use(
  '/reference',
  apiReference({
    url: '/openapi.json',
    withFastify: true, // Required when using Fastify adapter
  }),
)

The NestJS middleware takes our universal configuration object, read more about configuration in the core package README.

Themes#

The middleware comes with a custom theme for NestJS. You can use one of the other predefined themes (alternate, default, moon, purple, solarized) or overwrite it with none. All themes come with a light and dark color scheme.

import { apiReference } from '@scalar/nestjs-api-reference'
 
app.use(
  '/reference',
  apiReference({
    theme: 'purple',
    url: '/openapi.json',
  }),
)

Custom CDN#

You can use a custom CDN, default is https://cdn.jsdelivr.net/npm/@scalar/api-reference.

You can also pin the CDN to a specific version by specifying it in the CDN string like https://cdn.jsdelivr.net/npm/@scalar/api-reference@1.25.28

You can find all available CDN versions here

import { apiReference } from '@scalar/nestjs-api-reference'
 
app.use(
  '/reference',
  apiReference({
    cdn: 'https://cdn.jsdelivr.net/npm/@scalar/api-reference@latest',
    content: OpenApiSpecification,
  }),
)

Updated Sep 24, 2026