Mastodon

Mastodon is a microblogging application that's part of the Fediverse. It is free software and uses open standards to create a social media ecosystem that supports users rather than exploiting them as a product. Its servers are decentralized and run by volunteers or corporations, with moderation and user registration being decided by the server admin. Learn more on the Mastodon site.

Instances

social.wikimedia.de, operated by Wikimedia Deutschland, only WMDE staff and board members are allowed accounts (more details).
social.wikimedia.es, operated by Wikimedia España.
wikimedia.social (announcement), operated by the Wikimedia Foundation, only WMF staff are allowed accounts.
Wikis World, a Mastodon server for wiki enthusiasts, operated by volunteers
wiki.style, a wiki-themed Mastodon server, operated by volunteers

Accounts

Microblogging handles lists Mastodon handles for some Wikimedia affiliates, organizations and projects. Some accounts are largely managed on-wiki, including:

Furthermore, Wikidata has a property for Mastodon address that can be added to items on the platform. There are some regularly updated listeria lists of accounts such as d:Wikidata:List of free software accounts on Mastodon as well as a list of all items with Mastodon accounts (so far not populated due to a listeria bug but the WDQS query can be used).

Tools

The fedi-share tool can be used to create "share this page" buttons/links for Mastodon users.

Organizations

To get an inventory of Wikimedia Organizations using Mastodon, visit the page: FLOSS-Exchange.