ActivityPub is an open and decentralized protocol for social networking on the Internet. It is based on’s ActivityPump protocol and allows users to create, update, and delete content through a client/server API. Additionally, it enables servers to communicate with each other through a federated API for delivering notifications and content.

ActivityPub is considered a standard for the Internet and is part of the Social Web Networking Group of the World Wide Web Consortium (W3C). Originally named “ActivityPump,” the protocol was later renamed to ActivityPub to better reflect its purpose of cross-publishing. It is widely supported in the Fediverse, surpassing other standards.

ActivityPub was officially recognized as a Recommendation by the W3C in January 2018. This protocol, primarily developed by a team led by Christine Lemmer-Webber, specifically focuses on Internet publishing. It is worth noting that the team behind the protocol consists mainly of queer individuals, whose unique perspectives influenced the incorporation of features aimed at safeguarding against unwelcome interactions. Interestingly, the development of ActivityPub did not involve any participation from corporate entities.

The W3C Social Community Group hosts an annual conference called ActivityPub Conf, which focuses on discussing the future of ActivityPub. In the future, ActivityPub protocols may potentially facilitate the federation of Internet platforms.