
Lemmy
Self-hosted, ActivityPub-based forum platform for communities, link posts, and threaded discussions with federation across the Fediverse.

Lemmy is a community discussion and link aggregation platform similar to Reddit, designed for running topic-based communities with posts, comments, and moderation tools. It supports federation via ActivityPub, allowing separate Lemmy servers (and other Fediverse platforms) to interact while remaining independently managed.
Key Features
- ActivityPub federation between instances, including cross-instance communities and users
- Reddit-style content model: communities, posts (links/text), threaded comments, voting, sorting, and feeds
- Moderation tooling: community moderators, admin controls, reporting, bans, and content removal
- User and community management including roles/permissions and instance policies
- Multiple clients/frontends via API ecosystem (official and third-party web/mobile apps)
- Media handling via URL/link posts and integrations commonly deployed with reverse proxies and object storage
Use Cases
- Host a private or public community forum with familiar upvote/downvote dynamics
- Create a federated network of communities across multiple organizations or groups
- Replace centralized community platforms while keeping local control over policies and moderation
Limitations and Considerations
- Federation can introduce moderation complexity (remote content, defederation decisions, instance-level policies)
- Operationally requires a database and supporting services; upgrades should follow release notes to avoid breaking changes
Lemmy is well-suited for communities that want a modern discussion experience with federation and local autonomy. Its ActivityPub support and active ecosystem make it a practical choice for building interconnected forums without relying on a single centralized provider.






