Lemmy is free, open-source link aggregation software for running self-hosted discussion forums. Each server, called an instance, hosts communities where people post links and comments, and instances federate over ActivityPub so users can follow one another’s communities.
Lemmy belongs to the wider fediverse of interconnected servers, and this guide covers how it works, where it came from and what to weigh before joining.
What Lemmy is and how it is built
According to Wikipedia, Lemmy is a free and open-source, social news aggregation software for running self-hosted discussion forums. The project is written in Rust and TypeScript and released under the AGPLv3 license, which requires anyone who runs a modified version as a network service to offer the changed source code to its users.
The software was created by a GitHub user known as Dessalines in February 2019. The name has a casual origin. In a 2020 post the co-creator explained that he had been playing the old game Lemmings while the Motorhead musician Lemmy had died that same week, and that a few polls led him to the name.
The design resembles older link aggregators. Members submit a link, an image or a text post to a community, then others reply in threaded comments and vote. Lemmy differs from a centralised site in one basic respect: nobody owns the whole network. Anyone with a server can run an instance, set its rules and decide whom to admit.
How communities, voting and moderation work
Communities are the main organising unit. In the address bar a community appears with a c/ prefix, and across instances it is mentioned with the !community@instance format. A user on one instance can subscribe to a community hosted on another, and the posts appear in a personal feed alongside local ones.
Each instance front page shows popular posts from several communities, and the feed can be filtered by sort order or narrowed to subscribed communities only. Posts and comments can be upvoted or downvoted, although each instance’s admins can disable downvoting. That small switch shows how local control shapes the culture of a server.
Moderation is layered. Administrators govern an instance as a whole, while moderators look after individual communities. Admins can also decide which other instances to connect with or block, so a server with weak moderation may find itself cut off from others. Lemmy instances are generally supported by donations rather than advertising.
What a typical session looks like
A new member picks an instance, registers and lands on a front page of posts. From there the usual loop is simple: browse a feed, open a thread, read the comments, vote and reply. Subscribing to a community adds its posts to the personal feed, and a member can create a new community when no existing one fits a topic.
Because every instance sets its own sign-up rules, some ask for an application, some require email confirmation and others are open. Rules for content also differ. One server may be strict about off-topic posts, while another leaves most decisions to community moderators. Reading the sidebar and rules of both the instance and the community before posting avoids most early friction.
Third-party apps and alternative front ends exist, since the software exposes an API and its code is open. That openness is part of the appeal for people who left larger platforms after losing access to their preferred clients.
Federation through ActivityPub
ActivityPub is the protocol that lets Lemmy instances operate as one federated network. It also allows interaction with other compatible platforms, including Mastodon and the Kbin project, according to the same Wikipedia entry. In practice, a Mastodon user can follow a Lemmy community and see its posts, although the experience on each side differs because the interfaces are built for different habits.
Other fediverse projects take different shapes. The microblogging platform misskey centres on short posts with rich reactions, and pixelfed centres on photo sharing. Lemmy occupies the forum and link-sharing niche, so the three complement rather than replace one another.
Federation brings trade-offs. Content is copied between servers, so a deleted post may linger elsewhere, and a user’s account lives on one instance, meaning that an instance shutting down can strand its members. Choosing a stable, well-run instance matters more than it first appears.
Growth since the Reddit changes in 2023
Lemmy was a niche project for its first few years. Fediverse statistics sites recorded that it had fewer than 100 instances prior to June 2023. That month Reddit announced API service changes meant to curb third-party Reddit clients, and community members began discussing a move to Lemmy and other alternatives.
The surge was dramatic but not permanent. The same entry reports that Lemmy grew to 455 instances with approximately 48,600 monthly active users as of 22 December 2025. That figure is a small fraction of the audience of the large commercial forums, and it shows a network that is established and active but modest in size.
Development has continued as well. As of the Wikipedia entry’s latest update, the stable release was 0.19.21, dated 26 October 2026. A steady stream of point releases suggests the maintainers still treat the project as evolving, which matters for operators who must keep a server patched and compatible with its peers.
Is Lemmy a good fit?
Lemmy suits people who prefer topic-based discussion to personality-driven feeds, and who value control over their data and moderation rules. It tends to disappoint those who expect the size, search depth and polish of a large commercial site.
- Choosing an instance: look at its rules, its moderation record and who funds it, since the instance decides much of your daily experience.
- Finding communities: browse across instances rather than only the local list, because the best communities are often hosted elsewhere.
- Running your own: self-hosting gives full control, but the operator takes on moderation, updates and legal responsibility.
- Expectations: smaller communities mean fewer replies, but often calmer conversation.
Barnraiser is an independent editorial site with no affiliation to Lemmy or its developers, and it sells no hosting or software. Readers should check the project’s own documentation before choosing or deploying an instance.
Frequently asked questions
Is Lemmy the same as Reddit?
No. It copies the familiar format of communities, votes and threaded comments, but it is open-source software run by many independent servers rather than a single company.
Do I need an account on every instance?
No. One account on a single instance lets you subscribe to and post in communities hosted on other federated instances.
Who created Lemmy?
A GitHub user known as Dessalines created it in February 2019, and it is licensed under the AGPLv3.
Can Mastodon users see Lemmy posts?
Often yes. Both use ActivityPub, so compatible platforms such as Mastodon can interact with Lemmy, though the experience differs between them.
