Nuxt/docs/3.api/4.kit/11.nitro.md

---
title: "Nitro"
description: Nuxt Kit provides a set of utilities to help you work with Nitro. These functions allow you to add server handlers, plugins, and prerender routes.
---

# Nitro

[source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/nitro.ts)

Nitro is an open source TypeScript framework to build ultra-fast web servers. Nuxt 3 (and, optionally, Nuxt Bridge) uses Nitro as its server engine. You can use `useNitro` to access the Nitro instance, `addServerHandler` to add a server handler, `addDevServerHandler` to add a server handler to be used only in development mode, `addServerPlugin` to add a plugin to extend Nitro's runtime behavior, and `addPrerenderRoutes` to add routes to be prerendered by Nitro.

## `addServerHandler`

Adds a nitro server handler. Use it if you want to create server middleware or custom route.

### Type

```ts
function addServerHandler (handler: NitroEventHandler): void

export interface NitroEventHandler {
  handler: string;
  route?: string;
  middleware?: boolean;
  lazy?: boolean;
  method?: string;
}
```

### Parameters

#### `handler`

**Type**: `NitroEventHandler`

**Required**: `true`

A handler object with the following properties:

- `handler` (required)

  **Type**: `string`

  Path to event handler.

- `route` (optional)

  **Type**: `string`

  Path prefix or route. If an empty string used, will be used as a middleware.

- `middleware` (optional)

  **Type**: `boolean`

  Specifies this is a middleware handler. Middleware are called on every route and should normally return nothing to pass to the next handlers.

- `lazy` (optional)

  **Type**: `boolean`

  Use lazy loading to import handler.

- `method` (optional)

  **Type**: `string`

  Router method matcher. If handler name contains method name, it will be used as a default value.

### Examples

::code-group

```ts [module.ts]
// https://github.com/nuxt-modules/robots
import { createResolver, defineNuxtModule, addServerHandler } from '@nuxt/kit'

export default defineNuxtModule({
  setup(options) {
    const resolver = createResolver(import.meta.url)

    addServerHandler({
      route: '/robots.txt'
      handler: resolver.resolve('./runtime/robots.get.ts')
    })
  }
})
```

```ts [runtime/robots.get.ts]
export default defineEventHandler(() => {
  return {
    body: `User-agent: *\nDisallow: /`
  }
})
```

::

## `addDevServerHandler`

Adds a nitro server handler to be used only in development mode. This handler will be excluded from production build.

### Type

```ts
function addDevServerHandler (handler: NitroEventHandler): void

export interface NitroEventHandler {
  handler: string;
  route?: string;
  middleware?: boolean;
  lazy?: boolean;
  method?: string;
}
```

### Parameters

#### `handler`

**Type**: `NitroEventHandler`

**Required**: `true`

A handler object with the following properties:

- `handler` (required)

  **Type**: `string`

  Path to event handler.

- `route` (optional)

  **Type**: `string`

  Path prefix or route. If an empty string used, will be used as a middleware.

- `middleware` (optional)

  **Type**: `boolean`

  Specifies this is a middleware handler. Middleware are called on every route and should normally return nothing to pass to the next handlers.

- `lazy` (optional)

  **Type**: `boolean`

  Use lazy loading to import handler.

- `method` (optional)

  **Type**: `string`

  Router method matcher.

### Examples

::code-group

```ts [module.ts]
import { createResolver, defineNuxtModule, addDevServerHandler } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    const resolver = createResolver(import.meta.url)

    addDevServerHandler({
      handler: resolver.resolve('./runtime/uptime.get'),
      route: '/_handler'
    })
  }
})
```

```ts [runtime/timer.get.ts]
export default defineEventHandler(() => {
  return {
    body: `Response generated at ${new Date().toISOString()}`
  }
})
```

::

```ts
// https://github.com/nuxt-modules/tailwindcss
import { joinURL } from 'ufo'
import { defineNuxtModule, addDevServerHandler } from '@nuxt/kit'

export default defineNuxtModule({
  async setup(options) {
    const route = joinURL(nuxt.options.app?.baseURL, '/_tailwind')

    // @ts-ignore
    const createServer = await import('tailwind-config-viewer/server/index.js').then(r => r.default || r) as any
    const viewerDevMiddleware = createServer({ tailwindConfigProvider: () => options, routerPrefix: route }).asMiddleware()

    addDevServerHandler({ route, handler: viewerDevMiddleware })
  }
})
```

## `useNitro`

Returns the Nitro instance.

::alert{type=warning}
You can call `useNitro()` only after `ready` hook.
::

::alert{type=info}
Changes to the Nitro instance configuration are not applied.
::

### Type

```ts
function useNitro (): Nitro

export interface Nitro {
  options: NitroOptions;
  scannedHandlers: NitroEventHandler[];
  vfs: Record<string, string>;
  hooks: Hookable<NitroHooks>;
  unimport?: Unimport;
  logger: ConsolaInstance;
  storage: Storage;
  close: () => Promise<void>;
  updateConfig: (config: NitroDynamicConfig) => void | Promise<void>;
}
```

### Examples

```ts
// https://github.com/nuxt/nuxt/blob/4e05650cde31ca73be4d14b1f0d23c7854008749/packages/nuxt/src/core/nuxt.ts#L404
import { defineNuxtModule, useNitro, addPlugin, createResolver } from '@nuxt/kit'

export default defineNuxtModule({
  setup(options, nuxt) {
    const resolver = createResolver(import.meta.url)

    nuxt.hook('ready', () => {
      const nitro = useNitro()
      if (nitro.options.static && nuxt.options.experimental.payloadExtraction === undefined) {
        console.warn('Using experimental payload extraction for full-static output. You can opt-out by setting `experimental.payloadExtraction` to `false`.')
        nuxt.options.experimental.payloadExtraction = true
      }
      nitro.options.replace['process.env.NUXT_PAYLOAD_EXTRACTION'] = String(!!nuxt.options.experimental.payloadExtraction)
      nitro.options._config.replace!['process.env.NUXT_PAYLOAD_EXTRACTION'] = String(!!nuxt.options.experimental.payloadExtraction)

      if (!nuxt.options.dev && nuxt.options.experimental.payloadExtraction) {
        addPlugin(resolver.resolve(nuxt.options.appDir, 'plugins/payload.client'))
      }
    })
  }
})
```

## `addServerPlugin`

Add plugin to extend Nitro's runtime behavior.

::alert{type=info}
You can read more about Nitro plugins in the [Nitro documentation](https://nitro.unjs.io/guide/plugins).
::

### Type

```ts
function addServerPlugin (plugin: string): void
```

### Parameters

#### `plugin`

**Type**: `string`

**Required**: `true`

Path to the plugin. The plugin must export a function that accepts Nitro instance as an argument.

### Examples

::code-group

```ts [module.ts]
import { createResolver, defineNuxtModule, addServerPlugin } from '@nuxt/kit'

export default defineNuxtModule({
  setup() {
    const resolver = createResolver(import.meta.url)
    addServerPlugin(resolver.resolve('./runtime/plugin.ts'))
  }
})
```

```ts [runtime/plugin.ts]
export default defineNitroPlugin((nitroApp) => {
  nitroApp.hooks.hook("request", (event) => {
    console.log("on request", event.path);
  });

  nitroApp.hooks.hook("beforeResponse", (event, { body }) => {
    console.log("on response", event.path, { body });
  });

  nitroApp.hooks.hook("afterResponse", (event, { body }) => {
    console.log("on after response", event.path, { body });
  });
});
```

::

## `addPrerenderRoutes`

Add routes to be prerendered to Nitro.

### Type

```ts
function function addPrerenderRoutes (routes: string | string[]): void
```

### Parameters

#### `routes`

**Type**: `string | string[]`

**Required**: `true`

A route or an array of routes to prerender.

### Examples

```ts
import { defineNuxtModule, prerenderRoutes } from '@nuxt/kit'

export default defineNuxtModule({
  meta: {
    name: 'nuxt-sitemap',
    configKey: 'sitemap',
  },
  defaults: {
    sitemapUrl: '/sitemap.xml',
    prerender: true,
  },
  setup(options) {
    if (options.prerender) {
      prerenderRoutes(options.sitemapUrl)
    }
  }
})
```