Do Flatpak and pacman share dependencies on Arch Linux?

Flatpak runtimes are designed to be distribution-independent, which is why the same application can run across different Linux distributions. A Flatpak may therefore download libraries that are already present on your system, but it normally downloads them into Flatpak’s own storage rather than installing duplicate system packages. Firefox being installed through pacman won’t usually satisfy a Flatpak application’s dependencies.

They use separate dependency systems. pacman installs packages that integrate with your Arch system and can share libraries with other native applications. Flatpak apps run in a more isolated environment and use their own runtimes, so they generally don’t reuse the libraries installed by pacman. That does mean some components may be stored separately, although multiple Flatpak apps can share the same Flatpak runtime.

If you’re avoiding the AUR because you’re concerned about security, keep in mind that Flatpak isn’t automatically free from things you should inspect. You can review an AUR package’s PKGBUILD, while Flatpak applications have manifests and permissions worth checking. For many people, using a reputable AUR package and reviewing what it does is reasonable, but Flatpak is still a good choice when you want stronger isolation and portability.