A year with the fediverse

2024 was truly a year where I was deeply immersed in the fediverse. I worked on various projects, both large and small, related to the fediverse and ActivityPub, and some of them received quite positive responses from many people. I'm writing this to preserve these good memories.

What is the fediverse?

Let me briefly explain what the fediverse is—it's a network where different types of social media can communicate with each other. In other words, two accounts on completely different social media platforms can follow each other, comment on each other's posts, and like each other's content. Technically, this interoperability between different social media platforms is implemented using the W3C technical standard called ActivityPub.

Currently, notable social media platforms participating in the fediverse include Mastodon, Pixelfed, Akkoma, Misskey, WordPress, and many more projects too numerous to list. Most of them are also open source projects. Additionally, while not open source, Meta's Threads has been gradually implementing ActivityPub since this summer and can now be considered somewhat part of the fediverse.

Since it's a way for different social media platforms to communicate, accounts in the fediverse include not just a username but also a server name. This address format, commonly called a fediverse handle, looks similar to an email address: @username@host. Through this, accounts belonging to different servers and platforms can follow and communicate with each other. I also have a fediverse account, and you can follow me at @hongminhee@hollo.social.

Fedify

Fedify is probably my biggest achievement this year. Fedify is an ActivityPub server framework written in TypeScript, which I created because I couldn't find an appropriate level of abstraction for implementing ActivityPub servers. I initially tried building an ActivityPub server app from scratch several times and managed to create something that worked, but I wasn't entirely satisfied with the code. As I started writing it again with proper abstraction in mind, I realized I was essentially building a framework, and this made me deeply appreciate the necessity of an ActivityPub server framework like Fedify.

Fedify went through four rewrites—initially in TypeScript, then Python, then C#, and finally back to TypeScript. The language choice involved several considerations. First, it needed to support JSON-LD, ActivityPub's data exchange format, and needed to be somewhat dynamic to handle JSON-LD easily. Second, even as a dynamic language, it needed good static typing support, specifically what's known as gradual typing. Finally, it needed to have a large user base and rich ecosystem because I wanted Fedify to be widely used. After considering everything, I settled on TypeScript.

Including all the rewrites, I started working on it in early December last year, but counting from the final rewrite, I began development in late February and released the first version 0.1.0 in early March. Before release, I had planned to call it Fedikit, but just before release, I discovered there was already a project with the same name, so I quickly changed it to Fedify. The Python version I worked on under the codename Fedikit is still available on GitHub.

I can proudly say that Fedify currently provides the most comprehensive set of features needed for building an ActivityPub server. The fediverse isn't just about implementing ActivityPub—you need to handle many specifications including JSON-LD, Activity Vocabulary, WebFinger, NodeInfo, HTTP Signatures, Linked Data Signatures, and Object Integrity Proofs. Fedify covers all of these. In fact, Fedify implements many features that aren't even implemented in major ActivityPub implementations like Mastodon or Misskey. I often see people who mistakenly think implementing an ActivityPub server is simple after just skimming the ActivityPub spec, start without any ActivityPub framework, and end up overwhelmed by its complexity. I strongly recommend using Fedify for anyone thinking about building an ActivityPub server.

Another aspect I focused on while building Fedify was documentation. I believed it needed not just reference documentation but also comprehensive manuals covering all of Fedify's features. I would even write the manual documentation first before implementing new features. As a result, the documentation has grown quite extensive, and now I'm contemplating how to translate it into languages other than English.

Finally, my greatest achievement with Fedify was the Ghost's funding of Fedify. This allowed me to work on open source full-time for the first time in my life. Moreover, Ghost is Fedify's biggest user. Ghost's ActivityPub implementation is well underway and currently in private beta. It will likely be released to the public next year.

Hollo

Hollo is a single-user ActivityPub server. While people typically create fediverse accounts by joining a Mastodon or Misskey server they like, some software engineers prefer to set up their own server connected to their own domain name. However, software like Mastodon or Misskey is designed for multiple users and has many features unnecessary for single users, making it heavy and complicated to install. Hollo was created for such people. Hollo only needs PostgreSQL to run, making installation relatively simple, and it only includes features necessary for single users, which is its main advantage.

The background of creating Hollo is somewhat complex. Actually, Hollo could be said to be the catalyst for creating Fedify, as it was while starting to build an ActivityPub server like Hollo that I realized the need for an ActivityPub server framework. However, the code from that initial project wasn't reused in Hollo, and the project name wasn't even Hollo at that time, so strictly speaking, Hollo wasn't the direct cause for creating Fedify. But it's true that after creating Fedify, what I ultimately wanted to build was something like Hollo.

However, after creating Fedify, Fedify itself became what I wanted to focus on, and the original motivation somewhat faded. So by the time I actually started building Hollo, its main purpose had become creating a demo for Fedify. In fact, while building Hollo, I added needed features to Fedify and fixed bugs. However, since it was part of the Fedify project, Hollo's code quality is much lower compared to Fedify. I started addressing this issue after Hollo stopped being considered part of the Fedify project, but there's still much room for improvement in code quality.

Unexpectedly, Hollo gained a user base in Japan, leading me to translate the official documentation into Japanese and even set up a booth at an event called Open Source Conference 2024 Tokyo/Fall in Japan. At this event, I received tremendous help from Esurio, a local Hollo user who helped manage the booth with me.

Recently, for dogfooding, I migrated from my Mastodon account to Hollo.

FediDev KR

One day, I realized there wasn't much exchange between developers creating fediverse software in Korea. So I convinced Lee Jae-yeol, who had created a Mastodon client for Neovim, to help establish the FediDev KR. We first set up a Discord server where quite a few developers gathered.

We also planned regular sprint meetups and held our first meetup on August 31st at the returnzero office, which surprisingly attracted many participants. I still maintain connections in the fediverse with people I met there.

Recently, offline interactions have been less frequent due to the year-end, but we plan to resume active engagement next year.

First doujinshi sale

Since fall this year, I started actively engaging in the Japanese-speaking fediverse, which led to interactions with Japanese Hollo users. Among them, Esurio suggested participating in the Open Source Conference in Japan, and after some consideration, I decided to exhibit. Since it was my first time both participating in a Japanese event and setting up a booth, I received various forms of help from Esurio. I want to take this opportunity to express my gratitude.

Anyway, since we decided to exhibit, we needed something to display, so as part of this, I decided to print and sell a paper version of the Japanese translation of Fedify's tutorial Creating your own federated microblog (自分だけのフェディバースのマイクロブログを作ろう！). Fortunately, most of the books we brought were sold, so we could return quite light. One of the book purchasers, Monaco Koukoku (モナコ広告), even gave a talk titled I tried making an ActivityPub server with Fedify (FedifyでActivityPubサーバを作ってみた) at a FediLUG study meetup, sharing their experience following the tutorial.

It was great to interact with people, even those who didn't buy the book, despite my limited Japanese.

Full-time fediverse development

Unexpectedly, things have taken a direction I couldn't have predicted at the beginning of the year, and I've become a sort of full-time fediverse developer. Next year, I plan to focus on expanding the fediverse's foundation. As part of this effort, I'm working on creating an ActivityPub-based social platform for software engineers, which I hope to release soon.