Lemmy is similar to sites like Reddit, Lobste.rs, or Hacker News: you subscribe to forums you're interested in, post links and discussions, then vote, and comment on them. Behind the scenes, it is very different; anyone can easily run a server, and all these servers are federated (think email), and connected to the same universe, called the Fediverse. For a link aggregator, this means a user registered on one server can subscribe to forums on any other server, and can have discussions with users registered elsewhere. The overall goal is to create an easily self-hostable, decentralized alternative to Reddit and other link aggregators, outside of their corporate control and meddling. Each Lemmy server can set its own moderation policy; appointing site-wide admins, and community moderators to keep out the trolls, and foster a healthy, non-toxic environment where all can feel comfortable contributing. Features:

Open source, AGPL License. Self hostable, easy to deploy.

Comes with Docker and Ansible.

Clean, mobile-friendly interface. Only username and password are required to sign up! User avatar support. Live-updating Comment threads. Full vote scores (+/-) like old Reddit. Themes, including light, dark, and solarized. Emojis with autocomplete support. Start typing : User tagging using @, Community tagging using !. Integrated image uploading in both posts and comments. Flexible posts can consist of a title and a combination of self text, URL, or nothing. Notifications, on comment replies and when you're tagged.

Notifications can be sent via email.

Private messaging support. i18n / internationalization support. RSS / Atom feeds for All, Subscribed, Inbox, User, and Community. Cross-posting support. Automatic related post search when creating new posts. Great for question / answer communities and reposts. Moderation abilities.

Public Moderation Logs. Can sticky posts to the top of communities. Both site admins, and community moderators, who can appoint other moderators. Can lock, remove, and restore posts and comments. Can ban and unban users from communities and the site. Can transfer site and communities to others. Can fully erase your data, replacing all posts and comments. NSFW post / community support.

High performance.

Server is written in rust. Front end is ~80kB gzipped. Supports arm64 / Raspberry Pi.