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Recall guidance for developers of web browsers

  • 05/22/2025

Many web browsers support a concept of "InPrivate" browsing, where the user's history does not get saved.

To make sure that Recall doesn't save your user's browsing history while in modes like this, your app can use the SetInputScope function, setting the input scope to IS_PASSWORD.

Important

Your app must also have a http or https protocol handler registered before SetInputScope will support the behavior described in this article.

C# 
[DllImport("msctf.dll", SetLastError = true)]
private static extern int SetInputScope(IntPtr hwnd, InputScope inputScope);

private new enum InputScope : int
{
    IS_DEFAULT = 0,
    IS_URL = 1,
    IS_FILE_FULLFILEPATH = 2,
    IS_PRIVATE = 0x1f // Input is treated as private (e.g. passwords)
}

private void EnterInPrivateMode()
{
    // Get your HWND. This will vary based on your UI Framework. WPF can use WindowInteropHelper, passing in your current Window.
    IntPtr hwnd = new WindowInteropHelper(this).Handle;

    // Then, set the input scope on the HWND to private
    SetInputScope(hwnd, InputScope.IS_PRIVATE);
}

private void ExitInPrivateMode()
{
    // Get your HWND. This will vary based on your UI Framework. WPF can use WindowInteropHelper, passing in your current Window.
    IntPtr hwnd = new WindowInteropHelper(this).Handle;

    // Then, set the input scope on the HWND to default
    SetInputScope(hwnd, InputScope.IS_DEFAULT);
}

Your app should suspend providing user activities while the user is in "private" browsing mode.

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