MultiSync is a data hub for local-first apps that allows to sync append-only logs of ActivityStreams events between remote and local filesystems. It's important that clients read logs of events directly as files from S3-like remote filesystems.
Any ActityStream feed (for example Mastodon feed) can be converted to a series of Content Addressable aRchives, deployed to S3-like storage and made available as files for clients.
This allows to distribute public ActivityStream feeds as static files with near realtime updates using a fraction of costs required for standalone servers and significantly increase availability of data.
The MultiSync is used as a data exchange backend for local-first application Piki (hybrid of wiki and note-taking applications based on the ActivityPub protocol).