Sites that provide info about fediverse instances. 

* https://the-federation.info 

* https://fediverse.network - ActivityPub and OStatus only 

* https://podupti.me - diaspora-protocol networks only

* https://fediverse.space - Mastodon / Pleroma only (?)

* https://mnm.social - Mastodon only

* http://sp3r4z.fr/mastodon - Mastodon only

* https://distsn.org - microblogging (GNU Social, Mastodon, Pleroma, Misskey)

* https://lucahammer.at/vis/fediverse/2018-08-30-mastoverse_hashtags - ActivityPub and OStatus only (?)

* https://fediverse.joinout.de - OStatus protocol only

* https://mustafa.kotori.me - GNU Social only

* https://kumu.io/wakest/fediverse - visualization, OStatus protocol only (?)