Introduction

XDG Desktop Portal is a session service that provides D-Bus interfaces for apps to interact with the desktop.

Portal interfaces can be used by sandboxed and unsandboxed apps alike, but sandboxed apps benefit the most since they don’t need special permissions to use portal APIs. XDG Desktop Portal safeguards many resources and features with a user-controlled permission system.

The primary goal of portals is to expose common functionality and integration with the desktop without requiring apps to write desktop-specific code, or loosen their sandbox restrictions.

Terminology

  • Frontend: the XDG Desktop Portal service itself

  • Backend: desktop-specific implementation of portal interfaces

  • Host system: the privileged, unsandboxed part of the system stack

Reasons to use portals

Using XDG Desktop Portal brings major advantages over writing desktop-specific code for app developers:

  • Strict sandbox: portals enable sandboxed apps to access a curated set of features from the desktop environment and the host system, without weakening the sandbox of the app.

  • Unified code: by using portal APIs, apps only need to write a single desktop-agnostic code that runs on a variety of desktop environments. Portals can be used by sandboxed and unsandboxed apps alike. App developers are encouraged to use portal APIs even for unsandboxed apps.

  • Seamless integration: portal backends provide cost-free integration with the desktop. For example, simply using the File Chooser portal will make apps use the file picker dialog native to the desktop environment they’re running on.

  • Permission system: portals can restrict access to system resources through a permission system. Permissions can be granted, revoked, and controlled individually by the end user. This gives end users more control over apps.

In addition to the reasons above, some desktop features are primarily - and sometimes exclusively - available through portals. For example, the primary way of capturing screens and windows on Wayland desktops is through the ScreenCast portal, and some desktop environments don’t even expose other means to capture the screen or windows.