Hatsu is an open-source, self-hosted ActivityPub bridge for static sites. See its features, setup requirements, pros, cons and alternatives for 2026.
Category
Community Platforms
Pricing
Open Source, free, from Free (self-hosted)
Verified
Not yet
Last updated
July 18, 2026
Founded
2023
APIOpen SourceSelf-Hosted
Overview
Hatsu is a self-hosted, fully automated ActivityPub bridge that lets static websites federate with the Fediverse, the decentralized social network underlying platforms like Mastodon and GoToSocial, without adding a dynamic backend to the site itself. It reads a site's existing JSON Feed, Atom or RSS feed and uses that as its data source, rather than requiring HTML markup changes.
The project is written primarily in Rust, built on the Activitypub-Federation-Rust library also used by Lemmy, and is maintained by a GitHub developer known as importantimport under the AGPLv3 open-source license.
Key Features
Hatsu automatically creates ActivityPub actor profiles from a site's feed, redirects Fediverse searches for site pages or authors to the corresponding Hatsu-hosted profile, and accepts and distributes follower relationships as the feed updates with new posts.
It backfeeds replies from Fediverse users to the static site so Fediverse conversations can surface on the original content, implements HTTP signature verification for secure federation, and supports compatibility modes for Mastodon's secure mode and GoToSocial. Deployment is Docker-based for straightforward self-hosting, with aarch64 support for lower-powered hardware.
Pricing
Hatsu is entirely free and open source under the AGPLv3 license, with no company, subscription plans or paid tiers behind it.
The only costs involved are the server infrastructure an operator chooses to self-host Hatsu on and the time needed to configure DNS, reverse proxying and the feed source, since there is no managed hosting option or commercial support offering.
Key Features
Automated ActivityPub Actor Creation — Generates ActivityPub profiles automatically from a static site's existing content feed without requiring HTML markup changes.
Feed-Based Data Source — Reads JSON Feed, Atom or RSS as its source of truth instead of requiring microformats2-annotated HTML pages.
Fediverse Search Redirection — Redirects Fediverse searches for site pages or authors to the corresponding Hatsu-hosted profile or post.
Follower Management and Post Distribution — Accepts follow requests from Fediverse users and automatically distributes new posts to followers when the site feed updates.
Reply Backfeeding — Collects replies posted by Fediverse users and feeds them back to the static site so conversations can be displayed on the original page.
Mastodon and GoToSocial Compatibility — Supports Mastodon's secure mode and interoperates with GoToSocial for broader Fediverse platform compatibility.
Lightweight Rust Runtime with Docker Deployment — Built in Rust with aarch64 support and straightforward Docker-based self-hosting for low-resource environments.
Pros & Cons
Pros
Completely free and open source with no subscription cost or vendor lock-in
Works with any static site generator that produces a JSON Feed, Atom or RSS feed, not tied to one platform
Written in Rust for a lightweight, low-resource footprint suitable for modest self-hosted servers
Automates backfeeding of Fediverse replies, a capability many manual Webmention-based approaches lack
Actively maintained with regular releases and a public GitHub issue tracker for support
Cons
Requires self-hosting and server administration skills, with no managed hosting option available
Small project with a modest GitHub following, so community support and third-party tutorials are limited
ActivityPub-only, meaning it does not bridge to other decentralized protocols like Nostr or AT Protocol (Bluesky)
AGPLv3 license requires anyone distributing modified versions as a network service to release their source changes
No official commercial support channel exists for organizations needing SLA-backed assistance
Pricing
Open Source Free N/A
Frequently Asked Questions
What is Hatsu used for
Hatsu is used to let a static website participate in the Fediverse, allowing Mastodon and other ActivityPub users to follow the site, see new posts, and reply, without the site needing a dynamic backend.
Is Hatsu free to use
Yes, Hatsu is completely free and open source under the AGPLv3 license. There are no subscription plans; operators only pay for the server infrastructure they self-host it on.
Does Hatsu work with any static site generator
Yes, Hatsu works with any static site that produces a JSON Feed, Atom or RSS feed, including sites built with Hugo, Jekyll, Eleventy and Astro, since it reads the feed rather than requiring specific HTML markup.
What programming language is Hatsu written in
Hatsu is written primarily in Rust, built on the Activitypub-Federation-Rust library, the same library used by the federated platform Lemmy.
Does Hatsu support protocols other than ActivityPub
No, Hatsu is ActivityPub-only and does not bridge to other decentralized protocols such as Nostr or AT Protocol (Bluesky).
How is Hatsu different from Bridgy Fed
Hatsu is self-hosted, giving operators full control over their own instance, while Bridgy Fed is a hosted third-party service that performs a broadly similar bridging function without requiring self-hosting.