There is an official list of servers at https://joinmastodon.org/servers
I run an easy-to-use list at https://fedi.garden
Both lists require servers to adhere to certain requirements before being on the list.
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.