@notroot Unless you're making some other distinction I'm missing, ATProto is open source. It's not a proprietary system, and the various apps communicating with Bluesky (including private relays who have been able to talk to each other when Bluesky itself is down) do so using that open source standard.
Is there some other component I'm missing here?
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.