間
共
A calendar for the closest few
結び
M U S U B I
A quiet shared calendar — for two,
or for a small circle of trust.
No invitations. No notifications at 11 PM. No social graph. Just the people you actually plan things with, and the time you spend together.
v 1.0 · iOS & Android · 2026 · open source & MIT
原則 · Principles
Four ideas that quietly shape every screen.
間
Ma · Negative space
Room to breathe.
White space isn't empty. It's the pause that lets the eye settle on what matters — generous margins, unhurried lines.
侘寂
Wabi-Sabi · Restraint
Hairlines, not boxes.
Type and a single stroke can carry hierarchy. We skip cards, gradients, and shadows where a line will do.
静
Sei · Stillness
Motion that means it.
Transitions are short and eased. Nothing bounces or flashes for its own sake. (We promise. Mostly.)
共
Tomo · Together
A calendar belongs to a relationship.
Couples, households, climbing partners, the studio of six. Not feeds. Not org charts. People you'd answer the phone for.
中を覗く · A look inside
Three screens. That's most of the app.
三 つ
0 1 — お迎え
A welcome, not a wall.
Two buttons. No phone-number capture, no "are you sure?" loops.
0 2 — 週
The week you actually live in.
Filter by circle. Today wears Shu. Add an event with one tap.
0 3 — 予定
A list, when a grid is too much.
Quietly chronological. Yes, including "Call s Emou ❤".
色 · Five quiet hues
A small palette, drawn from old names.
Each calendar wears one of five traditional Japanese colors — all the same muted chroma, so no calendar shouts over another. (Yes, your in-laws get Indigo. Sorry.)
Bone 骨
Personal
For the things only you keep track of.
Shu 朱
Couple · Now
A red borrowed from the lacquer of old shrines. Marks today.
Moss 苔
Outdoors
Climbing partners, hiking, the early-morning crew.
Ochre 黄土
Studio
For the small creative group that makes a thing together.
Indigo 藍
Family
Sunday lunch. Birthdays you'd better not forget.
約束 · The quiet promise
What we won't do, in plain words.
We made Musubi because we wanted somewhere quiet to put our weekends. Not a product. A small room.
That's still the rule. Everything below follows from it.
01
Your time is yours. (WIP)
Events are end-to-end encrypted between the people in a calendar. We can't read "Call with Jenny ❤" and we don't want to.
02
No ads. No data sold.
Ever. If we run out of money we'll send you a letter, not a banner.
03
No social layer.
No discover. No friends-of-friends. You can only share a calendar with someone who is already in your phone.
04
Notifications worth keeping. (WIP)
One reminder. The right one. We'll never beep at you about engagement.
05
Leave with everything. (WIP)
Export to .ics any time. Take your knots with you.
公 · Open by default
Built in the open. Yours to read, fork, and run.
A calendar holds quiet things. So the code that holds them should be readable by anyone who cares to look.
Every line of Musubi — app, server, sync protocol — lives on GitHub under the MIT License. Self-host the whole thing, audit the encryption, or just lurk. We won't mind.
MIT
A permissive license.
Use it. Modify it. Ship it. Sell a fork on a different planet. The only ask: keep the copyright notice.
SELF
Self-hostable, end-to-end. (WIP)
Bring your own server with a single
docker compose up. Your knots, your hardware.DEV
Contributions welcome.
Issues, pull requests, translations, and small acts of yak-shaving. We read everything. Eventually.
SPEC
An open sync protocol. (WIP)
No proprietary lock-in. Build your own client in Rust, in Elm, in a spreadsheet — the wire format is specced and yours.
結
Tie one knot.
See if anything changes.
See if anything changes.
It's free. A small sponsor gift or subscription just unlocks some visual candy as a thank you, nothing more. (No free trial gimmicks. Just a real free tier.)