ActivityPub Rocks!

Blog posts with ActivityPub updates have moved to WordPress on the W3C's website

Johannes Ernst — Tue, 04 Aug 2026 14:21:00 +0000

At today’s meeting of the Website Task Force of the Social Web Incubator Community Group in the W3C – wow, that’s a handful! But that’s the group that has the responsibility of editing this site – we decided to use the WordPress blog that the W3C provides us with for future blog-style updates. And not have some updates here and some there, which confuses everbody.

The previous posts on this site are still here but some of the important onces have been back-ported over there, such as this one.

LOLA Portability for ActivityPub 0.3 available

Johannes Ernst — Mon, 15 Jun 2026 14:54:00 +0000

A new version of the LOLA Portability for ActivityPub specification is available, as Unofficial Draft 01 June 2026.

This is a minor bugfix release.

For more information about LOLA and why it matters, consider this post but Aaron Ayerdis Espinoza at the Data Transfer Initiative, who is one of the implementors of the specification.

Groups task force: initial draft adopted for task force report

Thu, 28 May 2026 17:43:00 +0000

Originally posted at: https://lists.w3.org/Archives/Public/public-swicg/2026May/0043.html

At today’s meeting, we adopted an initial draft of the Groups TF report.

Currently, it includes:

An introduction to what a “group” is, and how it might be distinguished from other usages of the term “group” across various specs and prior art, with relations to other work and other task forces
Some preliminary terms regarding membership and being a Member
Some initial user stories, with more to come – our GitHub issue tracker contains issues that need to be reviewed for user stories, and any user stories missing from the report will be eventually added. (If you have user stories to contribute that don’t currently have their own issue, please file issues for those!)
Potential approaches on how to become a member. Discussion in today’s meeting revolved around questions such as whether followers and members are or should be distinct, and what the properties of a membership are vs properties of an actor. Information from this discussion will hopefully be incorporated into the draft by next month, as well as expanded rationale for the distinction and the properties.

This post is soliciting feedback and participation from anyone interested in the work being done on Groups. Please provide any feedback in GitHub issues and/or on the mailing list.

RESOLVED: adopt https://swicg.github.io/groups/ as first working draft of TF report.

If there are any objections, please raise them within the next 2 weeks.

Initial Draft of Basic Profile for ActivityPub API Servers

Evan Prodromou — Tue, 19 May 2026 10:00:00 +0000

There is a new Basic Profile for ActivityPub API Servers initial draft put out by the ActivityPub API Task Force. Developers and community members are encouraged to provide feedback on the issue tracker for the task force.

ActivityPub defines a “ActivityPub API” that lets applications act on behalf of a user with a social networking platform. The ActivityPub API provides an extremely flexible interface for building social applications. Because unlimited kinds of activities can be created by clients, novel applications can be built on top of the ActivityPub network.

Unfortunately, the ActivityPub API has not been widely implemented in its read-write form, even by social platforms that implement the ActivityPub federation protocol. Those servers that have implemented it have taken opinionated steps in implementation, making it hard for client developers to achieve interoperability.

This profile is a step in the direction to improve the interoperability issue. It covers three important aspects of the API:

ActivityPub. It makes some concerted points about how the ids of ActivityPub objects are defined, and what behaviour a ActivityPub API server should implement.
OAuth 2.0. OAuth is the default API authorization framework, used by commercial APIs worldwide. However, it’s extremely flexible, which means that a client that implements OAuth will not necessarily implement the same profile as the server it’s trying to connect to. The Basic Profile selects some common options to make it easier to interoperate.
HTTP. There are a lot of options with RESTful APIs, like rate limits, CORS, and caching. The basic profile gives some suggestions on how to apply these tools correctly.

There’s a lot that’s not in the basic profile: push notifications, search, other endpoints. That’s the basic part – these extensions can be covered in other documents, and negotiated between client and server on a case by case basis. The basic profile is for the parts that are needed to get to that point!

There are a few open questions with this profile. The OAuth scopes are a first draft and don’t represent consensus; some task force participants suggest using Rich Authorization Requests also or instead. There are also very few MUST requirements; even supporting client-to-server interactions is a SHOULD.

Regardless, if you are interested, please consider reporting issues, and if you are a server operator, please consider implementing!

Maintaining activitypub.rocks going forward

Johannes Ernst — Wed, 03 Sep 2025 00:00:00 +0000

Hi all, this is Johannes Ernst, in my role as the lead of the website task force of the Social Web Community Group in the W3C.

As Christine just announced in another post, she is stepping down as the maintainer of this site. Maintenance of activitypub.rocks is passing to SWICG.

We are just starting, but we have a plan! Please refer to the issue tracker and the README.md in the repo for this site.

Want to help? PRs are appreciated. And, of course, you are welcome to join SWICG and help out.

Handing off activitypub.rocks to the ActivityPub community

Christine Lemmer-Webber — Thu, 28 Aug 2025 10:00:00 +0000

Hello everyone, Christine Lemmer-Webber here. I’m here to hand off this humble website, built and maintained by myself but, to be honest, not updated or stewarded nearly as well as I could have, to the broader ActivityPub community and the W3C Social Web Community Group in particular. Which is why I am handing it off. The last post I made to this website was in 2021, announcing some site updates, which were even then long overdue.

Time flies. On November 14th 2016, a period of time uncomfortably close to a decade ago, this website, activitypub.rocks, was launched. At the time, ActivityPub hadn’t even reached the Candidate Recommendation stage of the W3C process, though work had been going on it for a long time, and Mastodon had not begun adopting it either (Mastodon had just launched earlier that year and I hadn’t even heard of it at the time). ActivityPub would not become a W3C standard for another two years.

It was unclear at the time this website was created that ActivityPub would reach the level of success it has. ActivityPub has a long history, preceding even its work in the W3C process, with its most clear beginnings as the Pump.io API designed by Evan Prodromou. Erin Shepherd transformed pump.io’s API documentation into a draft of a specification document, and Jessica Tallon and I carried the document through the rest of the specification process, with some major rewritings by Amy Guy. But of course this leaves out much history too, and many contributors. There were many participants in the W3C Social Web Working Group where ActivityPub was originally standardized. And ActivityPub since has been driven by the implementers of the specification, of which there have been many, not to mention the numerous instance administrators and, of course, users who have made the fediverse such a special place.

This website was a small advocacy site put together by me, and has been continuously referenced as if the home of ActivityPub. And, effectively, when a thing is referenced as if it is the home of something on the web, often that effectively makes it the home. This website deserves better stewardship than just my own. So I am happy to hand it off so it can get the love and care it deserves.

But since we are moving through memory lane in this post, I thought I would end things with some historical artifacts I recently dug up. Though ActivityPub descended from pump.io’s API, the earliest implementations of ActivityPub as-specified were my own test implementations. They weren’t very good, and they weren’t really for anything but my own testing that the ideas of ActivityPub worked, but there were a few of them (including the test suite which, yes, was often down, but if you heard the rumor that it was built from the bones of a multiplayer text adventure game I wrote, those rumors are correct). But I thought I’d dig out a couple of screenshots for them, just for fun, just for history, just as a little parting gift.

Here is Pubstrate, a simple ActivityPub server I wrote in Guile (but which had some neat ideas, even though if it was only minimally usable), with these screenshots taken just shortly before this website was made:

Even at the time, preceding Peertube’s adoption, ActivityPub was intended for adoption across a wide variety of forms of media, not just microblogging:

Finally, it’s often forgotten that ActivityPub has not only a server-to-server protocol, it has a client-to-server protocol too! Here was soci.el, an emacs client for ActivityPub, being tested against Pubstrate:

But again, time flies. I’m grateful for the fediverse for keeping ActivityPub alive and making the work of myself and my colleagues so meaningful and worthwhile, such an honor to be part of. And I am grateful for the task force within the Social Web Community Group who are volunteering to steward and maintain and carry forward this humble website, and ActivityPub as a whole!

Onwards and upwards! See you on the fediverse!

Some (long overdue) site updates

Christine Lemmer-Webber — Mon, 04 Jan 2021 00:00:00 +0000

Hello, hello… it’s been about a year since SocialHub launched. This has been a successful community-run resource for discussing ActivityPub development and its future.

Since that time, a number of updates have been requested and suggested of this site. After significant delays (sorry), the frontpage of activitypub.rocks now better reflects the community-hosted resources where ActivityPub-oriented advancement and development have been happening. In particular, the link to the test suite, which has been down for ages (yes, sorry, we know), now instead points to the most excellent test.activitypub.dev. Massive thank you to cj of go-fed for providing this excellent and much-needed resource.

ActivityPub has come a long way since the days when this website first launched… at that time, the primary focus of this website was advocacy for the hope that ActivityPub would become a W3C-recommended standard. We’re well past those days now… the ActivityPub community is a flourishing one, with many implementations and more interest and users than ever. Today’s update makes a few small updates to better reflect such changing reality, and we hope to do so more moving forward. At the same time, we’re also happy that this website had to be updated to point to many external, community-oriented resources… a sign of a healthy community. May the future of ActivityPub be as bright as its present!

Let us meet on SocialHub!

Christine Lemmer-Webber — Thu, 26 Dec 2019 17:46:00 +0000

In case you missed the latest and hottest in the ActivityPub community, for a few months we have revived the SocialHub where developers, implementors, and anyone interested in the present and future of the W3C Recommendation gather, discuss issues, and collaborate with a kind and cooperative spirit to bring forth the best of what our collective intelligence can invent.

The new SocialHub, like the previous one we had to abandon, runs Discourse, a forum software that can be used via email, but shines on the web, and is about to implement ActivityPub support!

If you are implementing ActivityPub-compatible software, you’re very welcome to settle home on the SocialHub to give your project visibility and point potential contributors to your own community’s online resources (repositories, blog, forum, etc.). You can even use a subcategory dedicated to your software implementation to discuss ActivityPub-specific details with other developers for interoperability with your software.

Non-technical people are also welcome! There’s a lot to discuss, study, and invent in the growing Fediverse that has no equivalent in the surveillance capitalist counter-part that we’re escaping from. Our #Fediversity welcomes researchers, social scientists, journalists, and collectives interested in adopting ActivityPub for their own needs.

We’re also discussing how to make this site more useful for the world. Keep your eyes peeled!

You may leave comments to this article on the SocialHub!

ActivityPub reaches W3C Recommendation status! Everybody party!

Christine Lemmer-Webber — Tue, 20 Mar 2018 00:00:00 +0000

Ooops… this post was written months ago, but accidentally wasn’t pushed publicly till now! So… a delayed celebration to all!

We’re proud to announce that after a three year journey, ActivityPub is now a W3C Recommendation! Thank you and congratulations to the many, many people involved in this standardization effort. We couldn’t have done it without you.

Now comes the fun part… building ActivityPub applications! Join us in the Social Web Community Group to discuss ActivityPub implementation and new frontiers!

ActivityPub reaches Proposed Recommendation status!

Christine Lemmer-Webber — Fri, 08 Dec 2017 00:00:00 +0000

A little over one year later after reaching Candidate Recommendation status we’re pleased to announce that ActivityPub has now reached Proposed Recommendation status! (We actually moved to Proposed Recommendation status on Tuesday but… sometimes getting out news is a slow process.) This means that as far as the Social Working Group is concerned, the group is confident that ActivityPub is ready to become a real specification. Now we wait and cross our fingers for the W3C Membership and W3C Management to approve. Assuming all goes well, that would mean moving to Recommendation status sometime over the next couple of months.

In the meanwhile we’re seeing the number of ~~implementations of ActivityPub to be growing~~ (ed: obsolete and removed in 2026). What exciting new ActivityPub-using projects are on the horizon? We hope to see you submit your implementation to the implementation reports page next!

Test suite up, implementation reports page up... let's get more reports in!

Christine Lemmer-Webber — Mon, 06 Nov 2017 00:00:00 +0000

I’m happy to announce that the ~~ActivityPub test suite~~ is up and running. Likewise, so is the ~~implementation reports page~~ (ed: obsolete and removed in 2026)!

As it turns out, these go hand in hand. If you go through the test suite, it’ll generate an implementation report that you can easily submit. At the time of writing we have three implementation reports up, but we could really use more! Are you working on an ActivityPub implementation? Please submit one! Not only does it help ActivityPub get through the last leg of its standards process (we need to wrap up over the next few weeks!) but don’t you want to look cool by showing up as an implementation on the ~~implementation reports page~~ (obsolete and removed in 2026)? ;)

Note that it’s perfectly acceptable to incrementally submit reports… if it turns out that your implementation doesn’t pass as many items on the implementation report as you’d like, it’s okay to re-submit later. (At the time of writing, my own implementation Pubstrate has a number of items marked as not passing that I’ll be getting passing over the next few weeks!)

One note is that the test suite has two components: some of the tests are automated, and some of them prompt the user to manually test something and confirm/deny that it is passing. We would like to have full automated coverage in the future, but the working group agreed that since time is limited and interoperability is already being demonstrated externally through federation etc, this would be good enough for now. But it would be good to get more automated!

Anyway, we’re in the last mile of getting ActivityPub out the door. And if you’re an implementer, you can help us get there. Submit implementation reports, and help us, the world, ActivityPub’s standardization effort, and your project’s own vanity by getting an implementation report up there!

Mastodon launches their ActivityPub support, and a new CR!

Christine Lemmer-Webber — Sun, 10 Sep 2017 00:00:00 +0000

Greetings! Big news this week, from multiple directions!

Mastodon and ActivityPub, together at last!

First of all, Mastodon has launched version 1.6 with ActivityPub support! This is a huge piece of news. While Mastodon is not the first implementer of ActivityPub, they are by far the largest existing implementation, with approximately 850k registered users. We’re excited to have them on board!

A new Candidate Recommendation!

This week we published a new Candidate Recommendation (aka “CR”) of ActivityPub. This release contains two major changes:

Follow requests are now explicitly replied to with either an Accept or Reject.
publicInbox is now renamed to sharedInbox and in addition to being used for distributing and reading public posts, it may also be used to deliver posts to followers to reduce the number of HTTP requests made on followers-only posts between federated servers.

These changes are normative, so update your implementations!

The Candidate Recommendation is the period in which we try to stabilize the standard and get enough implementation to make it to Recommendation status. We don’t take normative changes lightly, but sometimes we such changes are found to be necessary in this stage… in this case, we found that both of these changes were necessary for Mastodon, and projects the size of Mastodon, to adopt ActivityPub.

What’s next?

We’ve quietly launched the test suite… very quietly, because not all test suite functionality is added yet! Only the “client-to-server server” section is yet working. However, we’re working on the rest of it and hope to have it up sometime within the next few weeks.

That’s it for now. Happy implementing, everyone!

New tutorial, new logo!

Christine Lemmer-Webber — Tue, 09 May 2017 15:10:00 +0000

A new Candidate Recommendation of ActivityPub has been released, and this one includes a really nice new feature… a tutorial! It includes some very nice illustrations by mray:

Not only that! mray has also done us the honor of designing us a sweet new logo:

Thank you mray for making ActivityPub look good!

Help submit implementation reports!

Christine Lemmer-Webber — Sun, 09 Apr 2017 00:00:00 +0000

This was done a while ago, but I forgot to update the website. Oops!

We’re happy to announce that ActivityPub is now ~~open for implementation report submissions~~ (ed: obsolete and removed in 2026)! In order for ActivityPub to transition from being a Candidate Recommendation to being a Proposed Recommendation, we need submissions showing that people are using the standard, and help identifying which features are used. (Filling in the implementation report has an added bonus: alongside following the standard, it’s a helpful checklist to make sure you’re implementing all the things you meant to!)

A huge thank you to Benjamin Goering for adding the implementation report template, which has helped tremendously! You rock, bengo!

What’s coming next? The test suite should be out as soon as possible! So if you start implementing now, you’ll be able to run against the test suite very shortly!

ActivityPub reaches Candidate Recommendation status!

Christine Lemmer-Webber — Thu, 17 Nov 2016 00:00:00 +0000

We’re thrilled to announce that ActivityPub has officially reached Candidate Recommendation status! This is a huge milestone, signaling that ActivityPub has moved to a point of stability where we’re no longer planning major revisions and would like to see as many projects move to implement as possible.

In other words, now’s a great time for YOU to start implementing! Head on over to the standard and start building!

We’re also planning tools to ~~test~~ your implementations soon, and ~~submit implementation reports~~ (ed: obsolete and removed in 2026). There’s a lot to do, but we’re on track towards being a proposed recommendation to the W3C!

activitypub.rocks launches!

Christine Lemmer-Webber — Mon, 14 Nov 2016 08:45:00 +0000

Today marks the launch of activitypub.rocks, the very website you see before you. This will be a combination of an advocacy website for ActivityPub as well as tooling to help test and collect feedback on implementations.

There should be more news soon. Hopefully we’ll be heading to Candidate Recommendation status shortly, and this very week the W3C Social Working Group is having another face to face meeting in Boston. So there will be hopefully more to report! In the meanwhile, if you’re hungry for news, you may enjoy this post on the MediaGoblin blog about the last Social Working Group face to face meeting.

Onward and upwards towards standardized, federated, decentralized social networks!