Pleroma is a free, open-source federated social networking server that speaks ActivityPub and works with Mastodon. It is written in Elixir and built to run on modest hardware, which makes it popular for small, self-hosted instances.
It is one of several servers in the fediverse, the loose network of independently run social platforms that exchange posts with each other.
What Pleroma is and where it came from
The project documentation describes it plainly: “Pleroma is a federated social networking platform, compatible with Mastodon and other ActivityPub implementations.” Wikipedia classes it as a free and open-source microblogging service, released under the AGPLv3 licence and written in Elixir and JavaScript. The name comes from a religious concept, the totality of divine powers.
Pleroma began as a frontend. As work on that frontend continued, developers found problems with the plugin-based design of GNU social and with its PHP codebase. That led to a new backend meant to replace it. The first commit to the Pleroma backend repository was made on March 17, 2017.
The backend uses the Elixir language and the Phoenix web framework, with PostgreSQL as its database. Elixir runs on the BEAM virtual machine, which handles many concurrent connections well. This is the usual explanation for why the server can stay small and still keep up with a federated workload.
How the backend and frontend fit together
According to the documentation, Pleroma “actually consists of two components: a backend, named simply Pleroma, and a user-facing frontend, named Pleroma-FE.” The backend handles federation, storage, moderation and the API. The frontend is the web interface people see when they log in.
The split matters because the frontend can be swapped. The default is Pleroma-FE, which was written with the Vue.js framework. Administrators can also install other interfaces. Wikipedia lists a port of Mastodon’s advanced mode, similar to TweetDeck, and an interface for the Gopher protocol. The documentation notes that the server also includes the Mastodon frontend for anyone who prefers it.
Pleroma was first developed with frontend and backend releasing in sync. Starting with Pleroma 2.6.1, that policy was discontinued, so the two now move on separate schedules.
Release history and recent versions
Pleroma 1.0 was released on June 28, 2019. Later releases added features that set it apart from other servers. Pleroma 2.6, released on October 29, 2023, implemented quoting posts and custom emoji for post reactions. Pleroma 2.7 followed on August 1, 2024, and added support for uploading files via IPFS, among other changes.
An earlier release added a federated instant messaging system built on ActivityPub. It works as an alternative to the direct messages used by software such as Mastodon.
As of Wikipedia’s listing, the latest stable release was 2.10.1, dated January 12, 2026. Readers planning an install should check the project’s release page for the current version, because that status changes over time.
Moderation with the Message Rewrite Facility
Instance administrators set their own code of conduct, terms of service and moderation rules. Pleroma adds a tool for this called the Message Rewrite Facility, or MRF. It lets administrators modify the content their instance sends and receives. Typical uses include rejecting posts from particular servers or stripping media from them.
MRF policies are modular. Custom ones can be written in any language that runs on the BEAM virtual machine. Because the list of active policies is shown publicly by default through both the API and the frontend, researchers have used MRF as a way to study how content moderation works across the fediverse. Visitors can see what an instance does before they sign up.
Pleroma compared with Mastodon and Misskey
The best-known server in the network is mastodon, and Pleroma is designed to interoperate with it. Pleroma uses a Mastodon-compatible API, so many Mastodon apps work with it. Pleroma generally targets smaller deployments and lighter hosting, while Mastodon is the reference point for large community servers.
Another option is misskey, which is also a microblogging server and leans on a different feature set and design. All three can exchange posts through ActivityPub, so the choice mostly comes down to interface, moderation tools and how much server a host wants to run.
| Aspect | Pleroma |
|---|---|
| Language | Elixir (backend), JavaScript (frontend) |
| Database | PostgreSQL |
| Licence | AGPLv3 |
| Default frontend | Pleroma-FE |
| Federation | ActivityPub |
Table details are drawn from the Wikipedia entry for Pleroma.
Choosing between the three
A person who wants the largest audience and the most polished apps will usually look at Mastodon first. Someone who wants to host a personal or family server on a small machine may find Pleroma easier to fit into a budget. Misskey draws people who want a different feel from the timeline and its tools. None of these choices locks anyone in, because accounts on one server can follow and reply to accounts on the others.
Differences still show up at the edges. Features such as quote posts, emoji reactions and direct messaging have been implemented in different ways across servers, so a post written on one may look slightly different on another. Readers who depend on a specific feature should test it on the server they plan to use before moving an account.
Who runs Pleroma
Pleroma is used mostly by individuals, friend groups and small communities that want control over their own server. The Debian community has also hosted its own microblogging service, part of its Debian Social effort. Self-hosting means the administrator is responsible for updates, backups and moderation. The documentation includes sections on backing up, restoring, moving and updating an instance for that reason.
Anyone considering Pleroma should weigh the tradeoffs. The software is light and flexible, but its community is smaller than Mastodon’s, so fewer guides and hosted options exist. Features can also differ from what Mastodon users expect.
Running an instance in practice
A new administrator needs a server, a PostgreSQL database and a domain name. The documentation covers installation, configuration and day-to-day tasks, including command-line tasks, database maintenance, email administration and emoji pack management. Settings can be moved between a configuration file and the database, which suits administrators who prefer to change options from the web dashboard.
The documentation also describes managing installed frontends. Since the frontend and backend release separately, an administrator can update the interface without touching the backend, or the reverse. This is useful when a frontend fix lands between backend releases.
Moderation is part of the job. An administrator who allows open registration will want to review the MRF policies before opening the doors, and decide which servers to limit or block. A small instance with a clear code of conduct and a few trusted users is far easier to manage than a large open one, and Pleroma is built with that smaller scale in mind.
New users who just want an account do not need to run anything. They can register on an existing instance, then follow people anywhere in the network. Browsing the public list of MRF policies on a candidate instance is a quick way to judge whether its moderation matches what they want.
Frequently asked questions
Is Pleroma compatible with Mastodon?
Yes. The Pleroma documentation calls it a federated platform compatible with Mastodon and other ActivityPub implementations, and it also bundles the Mastodon frontend as an option.
What is Pleroma written in?
The backend is written in Elixir with the Phoenix framework and uses PostgreSQL. The default frontend, Pleroma-FE, uses Vue.js.
What licence does Pleroma use?
Wikipedia lists the licence as AGPLv3, so the source code is free and open.
What is the Message Rewrite Facility?
MRF is Pleroma’s moderation system. It lets administrators change the content their instance sends and receives, using built-in or custom policies.
