Lemmy communities on any website.

Every Lemmy user, community, and post lives on a specific instance: a server running the open-source Lemmy software (Rust back end, TypeScript front end, AGPL license, source on GitHub). Examples include lemmy.world (the largest general-purpose instance, hosting most of the post-Reddit migration), lemmy.ml (the original instance run by the Lemmy developers), beehaw.org (a moderation-first community that defederated from lemmy.world during the 2023 governance moment), sh.itjust.works (general purpose, Canadian-hosted), programming.dev (developer-focused), lemm.ee (general purpose, Estonian-hosted), midwest.social, feddit.de, and hundreds of smaller and self-hosted instances. A community address like [email protected] tells the world the community name and which instance hosts it. Each instance has its own moderation policies, its own API endpoint at instance.tld/api/v3/, and its own community norms. There is no central Lemmy API to call. A widget that wants to embed a Lemmy feed must resolve the home instance from the address and talk to that server directly. Poper does this automatically: paste any community address and the widget hits the right instance API, caches the response at our CDN edge, and renders posts with the same fidelity as the Lemmy web client. If the home instance is slow or briefly down, the widget falls back to a peer instance that has federated the same community, which is one of the structural advantages of ActivityPub.

ActivityPub is the W3C-standard protocol that lets independent Lemmy instances talk to each other. When you subscribe to [email protected] from an account on lemmy.world, your home instance fetches that community's posts via ActivityPub and replicates them locally. From that point forward, lemmy.world has its own copy of the community feed, scores, and comments, kept in sync via federation. If lemmy.ml goes down for an hour during a server upgrade, lemmy.world still has a complete read replica. This is the same pattern Mastodon uses, the same pattern Pixelfed and PeerTube use, and the same pattern Threads adopted in 2024 when Meta added ActivityPub support. For embeds, federation matters most for resilience. The Poper widget queries a primary instance for the community feed; if the primary times out or returns an error, it queries a peer instance that has federated the same community and serves those posts instead. The reader sees the community feed regardless. This kind of cross-instance failover is impossible on centralized platforms (when Reddit goes down, every Reddit widget on every site goes down with it) and is one of the practical reasons brands and journalism collectives picked Lemmy specifically. ActivityPub support also extends beyond Lemmy: Mastodon, Pleroma, Akkoma, Misskey, Pixelfed, PeerTube, Mbin (a Lemmy-compatible aggregator), and Threads all speak the same protocol.

On June 1, 2023 Reddit announced that effective July 1, 2023 the Reddit Data API would move to a paid tier, charging $0.24 per 1000 calls above 10,000 calls per month per OAuth client. Apollo, the most popular third-party iOS Reddit app, calculated its bill at roughly $20 million per year and shut down on June 30. Reddit Is Fun, Sync, BaconReader, and Narwhal followed within weeks. The protest blackout in mid-June saw more than 8000 subreddits go dark. For users who already mistrusted corporate social, the API change was the trigger: roughly 700,000 net new users registered on Lemmy instances in June and July 2023, growing the network from a niche FOSS project of 50,000 users to a recognizable Reddit alternative within weeks. lemmy.world went from 1,000 users to over 150,000 in a month. beehaw.org, programming.dev, sh.itjust.works, and lemm.ee all saw similar growth. The lemmy.ml maintainers (Dessalines and Nutomic) went from a quiet weekend project to running infrastructure for hundreds of thousands of users overnight. The surge revealed both Lemmy's strength (federation distributed the load across hundreds of independent instances) and Lemmy's growing pains (the largest instances had to scale Postgres, the federation queue saturated briefly, and several instances added donation drives to cover hosting). For brands, the takeaway is that the Lemmy community now contains the most engaged, most ideologically committed, most technically literate Reddit refugees, which is a high-value audience for developer tools, privacy products, and open-source projects to reach via embeds.

Decentralization sounds clean in theory and is messy in practice. The clearest example on Lemmy is the June 2023 Beehaw moment. Beehaw.org was founded as a moderation-first community focused on kindness, with stricter content rules than larger general-purpose instances. After the post-Reddit migration surge brought a flood of new users to lemmy.world and sh.itjust.works, beehaw moderators saw an increase in low-effort posts, brigading, and harassment originating from those instances and could not keep up with manual moderation. On June 9, 2023, beehaw defederated from lemmy.world and sh.itjust.works, meaning content from those instances stopped flowing into beehaw and beehaw users could no longer participate in lemmy.world communities. The decision was controversial: some praised it as the federation working as intended (each instance can set its own policies), others criticized it as fragmenting the network, and lemmy.world admins published their own response committing to better moderation. The episode is required reading for anyone embedding Lemmy. It illustrates that Fediverse content is not uniform: a community on one instance may not be visible from another, defederation can change instance reachability with no notice, and a widget that hardcodes a single home instance can break when governance shifts. The Poper widget handles this by resolving community addresses dynamically, supporting peer fallback across multiple federated mirrors, and surfacing instance attribution clearly in each post card so readers know which instance served the content.

Lemmy is licensed AGPL-3.0, the same copyleft license as Mastodon. The AGPL has a network-use clause: anyone who runs a modified Lemmy instance and serves it over a network must publish the source code for those modifications. Practically, this means every Lemmy instance you embed from is required to make its source available, every fork (LemmyBB, Mbin, etc.) must release its changes, and Lemmy can never be fully captured by a corporate owner the way Reddit was during its IPO arc. The license is not just a legal detail; it is a values statement that shapes what the platform does. Lemmy instances do not run analytics scripts, do not load tracking pixels, do not fingerprint visitors, and do not phone home. There is no advertising on Lemmy. There is no algorithmic feed designed to maximize engagement. There is no data sale to AI training partners. A widget that breaks this pattern by injecting cookies, tracking pixels, or fingerprinting libraries violates the platform's culture and gives privacy-aware visitors a reason to bounce. Poper ships a Lemmy embed that respects these values: no cookies set by the widget, no tracking calls to third parties, no fingerprinting, and a privacy policy that explicitly does not collect personal data from widget interactions. For GDPR-heavy sites (European media, academic institutions, healthcare, public-sector), this is a practical advantage: the embed does not trigger the cookie banner, does not require additional consent management, and does not appear in any data processing agreement audit. Combine that with respect for native sort modes, cross-post merging, and instance attribution, and the embed feels native to Lemmy, not bolted on from a corporate social tool.