---
modificationDate: April 03, 2026
title: Inline modules reference
description: A reference of Expo inline modules.
---

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# Inline modules reference

A reference of Expo inline modules.

> For the complete documentation index, see [llms.txt](/llms.txt). Use this file to discover all available pages.

> Inline modules are [experimental](/more/release-statuses#experimental). The API is subject to breaking changes.

Inline modules let you write native module code (Kotlin and Swift) directly in your Expo project directory, without creating a separate Expo module package. Expo discovers these files automatically and includes them in the build.

## Configuration

### `expo.experiments.inlineModules`

When defined, enables inline modules functionality in Expo CLI and Expo Modules Autolinking.

```json
{
  "expo": {
    "experiments": {
      "inlineModules": {}
    }
  }
}
```

### `expo.experiments.inlineModules.watchedDirectories`

Configures in which directories the inline modules can be created.

```json
{
  "expo": {
    "experiments": {
      "inlineModules": {
        "watchedDirectories": ["app", "src"]
      }
    }
  }
}
```

Files inside nested directories will also be used. For example, if `watchedDirectories = ["app"]` is defined in the app config, and a module file such as **app/nested/directory/SomeModule.kt** exists in a nested path, then `SomeModule` can be used in your app.

A directory in `watchedDirectories`:

-   Needs to be inside a TypeScript/JavaScript project. This means it needs to have an ancestor in the directory tree that has **package.json**. For example, `"watchedDirectories": ["app", "src/some/directory", pathToOtherProject]` should work and `"watchedDirectories": ["/", pathToFolderNotInNodeProject]` won't.
-   Cannot be the whole project directory, for example,`"./"`, nor an ancestor of it (for example `../`).
-   Cannot be a subdirectory of the other directory in `watchedDirectories`. For example, `watchedDirectories` cannot be `["app", "app/nested/directory"]`, you can just set `watchedDirectories` to `["app"]`.
-   Cannot contain special characters like `" ", "(", ")", "$"`. This means you cannot have `"app/(tabs)"` in the `watchedDirectories`, but you can have `"app"` and it should still use native files from `"app/(tabs)"` directory.

> You need to run `npx expo prebuild` after changing the [app config](/workflow/configuration), for it to take effect.

## Naming convention

The inline module file name has to match the native module name (which needs to be unique in your whole app). If you have a **SimpleModule.kt**, then the inline module inside it has that file name. For example:

```kotlin
// SimpleModule.kt
// ...
class SimpleModule: Module() { // Note that the class name has to match the filename.
    public func definition() -> ModuleDefinition {
        // Name("SimpleModule") // Note that `Name` also has to match the filename. So you can just omit it.
    }
}
```