Sync that merges, not overwrites

Automerge CRDT

Your collection is a CRDT: an Automerge document. Two devices can edit the same deck while offline, and when they meet, both sets of changes merge. There is no last-write-wins overwrite of a whole file and no conflict dialog asking you to choose between versions of your own notes.

Merge is deterministic, so the result does not depend on which device reconnects first. That is what makes offline work usable: you can study on a train, add cards on a laptop the same evening, and end up with both sets of edits in the morning.

Automerge is also what lets the same collection be edited from a browser tab and a phone without a merge step you have to trigger yourself.

Direct to your storage

The client uploads to object storage directly, using short-lived credentials scoped to that account’s prefix. The server mints those credentials and records account, billing, and sync metadata; it never stores your payload bytes.

Short-lived, prefix-scoped credentials keep the blast radius small: a token that leaks is limited both in time and in which part of the bucket it can reach. The control plane stays a small metadata service rather than a proxy for every note you write.

Because the server only holds metadata, a control-plane outage does not take your notes with it: the last uploaded changes stay in your bucket, and the client can keep editing locally until the service is reachable again.

A status you can trust

A status pill reports what is actually happening: backed up, saving to cloud, offline, not backed up, local only, or needs attention. When you are offline it says so, and your changes stay queued on the device until the connection returns.

The pill distinguishes local-only from offline on purpose. One is a setting you chose, and the other is a temporary condition; showing the same message for both would be a small lie repeated every day.

Miyu Sync

Sync is $4.99/month after a 14-day free trial, with 10 GB of cloud storage. If you stop, the local collection is untouched: syncing pauses and everything stays readable on the device.

The subscription pays for storage and sync. The app itself stays free, and nothing in the local workflow depends on keeping the subscription alive.