Run the following steps from a directory containing the gajim source dir. Install gajim flatpak repo -------------------------- 1. `flatpak --user remote-add --from gnome https://sdk.gnome.org/gnome.flatpakrepo` 1. `flatpak --user install gnome org.gnome.Platform//3.26` 1. `flatpak --user install gnome org.gnome.Sdk//3.26` 1. `flatpak-builder --repo=repo directory gajim/org.gajim.Gajim.json` 1. `flatpak --user remote-add --no-gpg-verify repo repo` 1. `flatpak --user install repo org.gajim.Gajim` 1. `flatpak run org.gajim.Gajim` Update gajim flatpak repo ------------------------- 1. update your gajim source repository 1. `rm -r directory` 1. `flatpak-builder --repo=repo directory gajim/org.gajim.Gajim.json` 1. `flatpak --user update` Note: remove `--user` if you want a system-wide installation