About Musubi
Musubi (結び — "to tie together") is a shared calendar for the handful of people you actually plan with. One person builds it in the open; a small EU company keeps it running.
What Musubi is.
One calendar, tied to the people you actually plan with — no feeds, no ads, no data sold.
Musubi pulls your Google, Apple, Outlook and CalDAV calendars into a single two-way-synced view, then lets you share a calendar with just the few people you invite — your partner, the household, a small crew. Anything you write in Musubi flows back to the original calendar, and changes there flow into Musubi.
There is no activity feed, no friend discovery, and no social layer. It is a quiet tool for coordinating with the closest few, not a network to grow.
Who makes it.
Musubi is built by Filip Tůma, working in the open under FRGTN. The app, server and sync protocol are developed as a single open-source project rather than behind closed doors, and the roadmap and issues are public.
It is a small, independent effort — the kind of software written by people who use it themselves every day, not assembled by a growth team. If you want to see how a decision was made, the commit that made it is public.
How we think about privacy.
We don't sell your data or run ads. We're also honest that the server reads events to sync them — Musubi is private, not end-to-end encrypted.
Calendars reveal a lot: where you are, who you see, when you're free. So Musubi is invite-only by design — a calendar is shared through a link you create, with the specific people you choose, and nobody else.
We won't pretend to a guarantee we can't keep: to sync your calendars two ways, the server processes your events. It is not end-to-end encrypted. What we can promise is that your data is never sold, never used for advertising, and never mined for a social graph. The full detail lives in the Privacy Policy.
Open source.
Musubi is released under the MIT License. You can read every line, file an issue, send a patch, or run the whole thing yourself — the server self-hosts with a single docker compose up. The source lives on GitHub, and setup and self-hosting are covered in the docs.
Open source is also the trust model: you don't have to take our word for how Musubi handles your data — you can check.
The company.
Musubi is operated by forgotten s.r.o., IČO 23642467, Nové sady 988/2, Staré Brno, 602 00 Brno, Czech Republic, registered at Krajský soud v Brně, file no. C 146736.
The service runs on EU infrastructure (Hetzner, Germany) over HTTPS. Android is in open beta on Google Play; iOS open testing is coming. Musubi is free during the open beta.
Contact.
Questions, bug reports, or just want to say hello? Email [email protected], open an issue on GitHub, or share what you'd like to see on the roadmap.