ActivityPub

The ActivityPub protocol is a decentralized social networking protocol based upon the [ActivityStreams] 2.0 data format. It provides a client to server API for creating, updating and deleting content, as well as a federated server to server API for delivering notifications and content.

Activity Streams 2.0

Please check the errata for any errors or issues reported since publication.

ActivityPub Client API: A Way Forward | Steve Bate

The ActivityPub Client-to-Server (C2S) protocol was envisioned as a cornerstone of the decentralized social web, along with the Server-to-Server (S2S) protocol. Standardized by the W3C in 2018, C2S defines how user-facing applications, such as mobile apps or web clients, and bots should interact with social servers using Activity Streams 2.0 and JSON-LD. In theory, it ... Read more

Concise Binary Object Representation (CBOR)

The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack. This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format.

Integrating ActivityPub within Solid specs

I’ve been spending a bit of time catching up on this discussion and experimenting. I have successfully subscribed to remote ActivityPub actors and processed inbox activities. (My write-up: JG10 Solid devlog ) I ended up using an architecture not yet mentioned here, in which the inbox and outbox are public append LDP containers that receive activities. Solid notifications are used to notify an external agent that reads the new activity and processes it. This works because Solid already supports...

snac2

A simple, minimalistic ActivityPub instance written in portable C

ActivityPub

ActivityPub is a protocol and open standard for decentralized social networking. It provides a client-to-server (C2S) API for creating and modifying content, as well as a federated server-to-server (S2S) protocol for delivering notifications and content to other servers. ActivityPub is the defining standard of the Fediverse, a decentralised social network of various social interaction models, and content types, which consists of independently managed instances of software such as Mastodon, Pixelfed and PeerTube, among others.

Protocol Buffers

Protocol Buffers are language-neutral, platform-neutral extensible mechanisms for serializing structured data.

ActivityPub, AT Protocol, and more!

Talking about this article and how ActivityPub and AT Protocol are maybe not as different as people might think. We covered some slides to an unrecorded talk of mine, which explores a lot of things...

Episode #140: Eli Mallon - Streamplace and the future of decentralized video streaming

This week we're joined by Eli Mallon, founder of Streamplace, a decentralized video streaming platform. In this episode we discuss the future of decentralized video streaming, the challenges of building a new platform, and how developers can leverage Streamplace's tools. We also go into Atproto, the decentralized social media network that stream place is built on. - https://stream.place/about - https://techcrunch.com/2025/04/04/beyond-bluesky-these-are-the-apps-building-social-experiences-on-the-at-protocol - https://github.com/iameli - https://www.linkedin.com/in/eli-mallon-5703a94a - https://bsky.app/profile/iame.li - https://www.livepeer.org/ Episode sponsored By WorkOS (https://workos.com) and Mailtrap (https://l.rw.rw/devtools_2) Become a paid subscriber our patreon, spotify, or apple podcasts for the full episode. - https://www.patreon.com/devtoolsfm - https://podcasters.spotify.com/pod/show/devtoolsfm/subscribe - https://podcasts.apple.com/us/podcast/devtools-fm/id1566647758 - https://www.youtube.com/@devtoolsfm/membership

ActivityPods - Personal data spaces powered with ActivityPub

Brings together ActivityPub and Solid Pods and empowers developers to create truly decentralized applications.

CBOR — Concise Binary Object Representation | Specification

CBOR is specified in an Internet Standard RFC. RFCs that serve as Internet Standards are generated by the IETF based on an extensive technical review and quality control process. These are meant to last.

ActivityPub Won by Being Boring

At FediForum 2026, ActivityPub co-author Evan Prodromou explained why the protocol succeeded by staying deliberately ordinary and why the W3C's Q3 2026 revision needs to keep it that way.