Hatsu

Hatsu is a bridge service that lets static websites participate in the Fediverse by exposing site users and posts as ActivityPub actors and objects. It automates discovery, follow handling, posting to followers, and backfeeding replies using site feeds.

Key Features

• Maps site-level user identifiers and URLs to ActivityPub actors and object URIs for federation
• Uses site feeds (JSON / Atom / RSS) as the source of truth for create/update detection
• Automatically accepts follow requests and delivers new posts to followers' inboxes
• Receives replies from Fediverse actors and backfeeds them to the originating static site (backfeed feature is a work-in-progress)
• Performs HTTP signatures for outgoing requests to improve compatibility with secure Mastodon and GoToSocial instances
• High-performance Rust backend with Docker deployment support and aarch64 builds
• Designed to work with any static site generator and many static hosting setups

Use Cases

• Enable a static blog or website to have Fediverse accounts for authors and posts without running a full social server
• Push new site content automatically to followers on Mastodon-compatible servers
• Collect replies and interactions from the Fediverse and surface them back to a static site

Limitations and Considerations

• ActivityPub-only: does not support other social protocols such as Nostr or AT Protocol
• Some backfeed functionality is still marked as work-in-progress and may have limited features
• Compatibility nuances can exist across Fediverse implementations; HTTP signature behavior and compatibility modes are provided to mitigate interoperability issues

Hatsu provides a focused, automated bridge for static sites to participate in ActivityPub federation with minimal ongoing maintenance. It is suitable for site owners who want Fediverse presence without running a full social platform.