Nuxt auto-imports helper functions, composables and Vue APIs to use across your application without explicitly importing them. Based on the directory structure, every Nuxt application can also use auto-imports for its own components, composables and plugins. Components, composables or plugins can use these functions.
Contrary to a classic global declaration, Nuxt preserves typings and IDEs completions and hints, and only includes what is actually used in your production code.
You can find a reference for auto-imported [composables](/docs/api/composables/use-async-data) and [utilities](/docs/api/utils/dollarfetch) in the API section.
You can also auto-import functions exported from custom folders or third-party packages by configuring the [`imports` section](/docs/api/configuration/nuxt-config#imports) of your `nuxt.config` file.
Nuxt auto-imports functions and composables to perform [data fetching](/docs/getting-started/data-fetching), get access to the [app context](/docs/api/composables/use-nuxt-app) and [runtime config](/docs/guide/going-further/runtime-config), manage [state](/docs/getting-started/state-management) or define components and plugins.
When you are using the built-in Composition API composables provided by Vue and Nuxt, be aware that many of them rely on being called in the right _context_.
During a component lifecycle, Vue tracks the temporary instance of the current component (and similarly, Nuxt tracks a temporary instance of `nuxtApp`) via a global variable, and then unsets it in same tick. This is essential when server rendering, both to avoid cross-request state pollution (leaking a shared reference between two users) and to avoid leakage between different components.
That means that (with very few exceptions) you cannot use them outside a Nuxt plugin, Nuxt route middleware or Vue setup function. On top of that, you must use them synchronously - that is, you cannot use `await` before calling a composable, except within `<script setup>` blocks, within the setup function of a component declared with `defineNuxtComponent`, in `defineNuxtPlugin` or in `defineNuxtRouteMiddleware`, where we perform a transform to keep the synchronous context even after the `await`.
If you get an error message like `Nuxt instance is unavailable` then it probably means you are calling a Nuxt composable in the wrong place in the Vue or Nuxt lifecycle.
See the full explanation in this [comment](https://github.com/nuxt/framework/issues/5740#issuecomment-1229197529).
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#### Example
**Example:** Breaking code:
```ts [composables/example.ts]
// trying to access runtime config outside a composable
const config = useRuntimeConfig()
export const useMyComposable = () => {
// accessing runtime config here
}
```
**Example:** Fixing the error:
```ts [composables/example.ts]
export const useMyComposable = () => {
// Because your composable is called in the right place in the lifecycle,