> ## Documentation Index
> Fetch the complete documentation index at: https://filekit.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# File saver dialog

> Open a file saver dialog in a Kotlin Multiplatform project

<Check>Supported on Android, iOS, macOS and JVM targets</Check>

## Quick start

The file saver component provides a native interface for users to choose where to save a file on their device.

The file saver dialog returns a `PlatformFile` object representing where the user wants to save the file. Note that the file is not created automatically - it's the developer's responsibility to write the actual data to the file location using methods like `write()`.

Here's a basic example:

<CodeGroup>
  ```kotlin filekit-dialogs theme={null}
  // Open file saver dialog
  val file = FileKit.openFileSaver(
      suggestedName = "document",
      defaultExtension = "pdf",
  )

  // Write your data to the file
  if (file != null) {
      file.write(bytes)
  }
  ```

  ```kotlin filekit-dialogs-compose theme={null}
  val scope = rememberCoroutineScope()
  val launcher = rememberFileSaverLauncher { file ->
      // Write your data to the file
      if (file != null) {
          scope.launch {
              file.write(bytes)
          }
      }
  }

  Button(onClick = {
      launcher.launch(
          suggestedName = "document",
          defaultExtension = "pdf",
      )
  }) {
      Text("Save file")
  }
  ```
</CodeGroup>

## Parameters

The file saver can be customized with several parameters:

* `suggestedName`: The default name for the file without extension
* `defaultExtension`: The default file extension without the dot (e.g., "pdf", "txt")
* `allowedExtensions`: The allowed save extensions without dots (e.g., `setOf("txt", "md")`). This is a native dialog hint, not a validation guarantee.
* `directory`: The starting directory for the save dialog
* `dialogSettings`: Platform-specific settings for customizing the dialog behavior

<CodeGroup>
  ```kotlin filekit-dialogs theme={null}
  val file = FileKit.openFileSaver(
      suggestedName = "my-document",
      defaultExtension = "pdf",
      allowedExtensions = setOf("pdf", "txt"),
      directory = PlatformFile("/custom/initial/path"),
      dialogSettings = FileKitDialogSettings.createDefault()
  )
  ```

  ```kotlin filekit-dialogs-compose theme={null}
  val launcher = rememberFileSaverLauncher(
      dialogSettings = FileKitDialogSettings.createDefault()
  ) { file ->
      // Handle the selected save location
  }

  launcher.launch(
      suggestedName = "my-document",
      defaultExtension = "pdf",
      directory = PlatformFile("/custom/initial/path"),
      allowedExtensions = setOf("pdf", "txt"),
  )
  ```
</CodeGroup>

Use `defaultExtension` for the default file name and default extension. Use `allowedExtensions` when the native save dialog should offer specific save types. Filtering is applied where the platform supports it; apps that require a specific output format should still validate the returned file extension.

Read more about [dialog settings](/dialogs/dialog-settings) to customize the dialog for each platform.

## Writing data

The file saver returns a `PlatformFile` object representing the selected save location. You can write data to this file using the `write()` extension function:

```kotlin theme={null}
val file = FileKit.openFileSaver(suggestedName = "document", defaultExtension = "pdf")

if (file != null) {
    // Write bytes to the file
    file.write(bytes)
}
```

For more information about writing files, see the [write file guide](/core/write-file).

## Download file on the web

On web targets (JS and WASM), instead of using a file saver dialog, you can directly download a file using `FileKit.download()`:

```kotlin theme={null}
// Download bytes
FileKit.download(
    bytes = "Hello, World!".encodeToByteArray(),
    fileName = "hello.txt"
)

// Download from a PlatformFile
val file: PlatformFile = ...
FileKit.download(file, fileName = "document.pdf")
```

This will trigger the browser's native download behavior, saving the file to the user's default downloads directory.

<Info>
  On web targets, the file saver dialog is not supported due to browser security restrictions. Instead, use `FileKit.download()` to download files directly.
</Info>

For more information about writing files on different platforms, see the [write file guide](/core/write-file).