Restfox is a minimalistic, offline-first HTTP and socket testing client designed for both web and desktop platforms.
Assuming flatpak, flatpak-builder, and git are installed, execute the following commands:
$ git clone https://github.com/flathub/dev.restfox.Restfox.git
$ cd dev.restfox.Restfox/
$ flatpak remote-add --if-not-exists --user flathub https://flathub.org/repo/flathub.flatpakrepo
$ flatpak-builder build --force-clean --install-deps-from=flathub --install --user dev.restfox.Restfox.yaml
# To uninstall the artifact
$ flatpak uninstall --delete-data --user dev.restfox.Restfox
# And to clean-up everything
$ rm --force --recursive .flatpak-builder/ build/
$ flatpak uninstall --unused --user
$ flatpak remote-delete --user flathub