Your notes, in files you own

One collection, every profile

Profiles share one collection on disk. Decks, cards, courses, presets, note types, and the review log live together, and every profile is included in the same backup. Because the collection is a folder rather than a database you cannot read, moving to a new machine is a copy rather than a migration wizard.

Profiles separate study material and review history without splitting the files. A shared machine with two learners is two profiles in one folder, not two installations to keep in step. Switching profiles changes what you see, never what is backed up.

Plain Markdown

Each note is its own Markdown file under notes/, with front matter for its identifiers and fields. Decks, courses, and presets are small JSON files, and review history is appended to monthly JSONL shards.

Front matter carries the identifiers; the body stays prose. A diff of two exports is readable, and a note copied into another editor keeps its text even if Miyu never sees it again. Any text editor can open the notes, which is the point: a note written today stays readable years from now, with or without the app.

Backups you can verify

Miyu writes automatic backups on the device whether or not sync is on. Older backups are deleted after the retention window, but the newest is always kept until a replacement exists. Restoring verifies the archive and takes a safety backup first, so a bad restore cannot erase the collection it was meant to rescue.

The retention window is a setting, which makes the trade-off explicit: keep more history and spend more disk, or keep fewer and accept a shorter undo window. Pruning never leaves you without a backup.

Optional sync, not required

Sync is a choice, not a precondition. Turn it off and the collection stays local while the app keeps working offline. Turn it on and changes merge with what other devices wrote.

Storage follows the platform: a folder on desktop, local storage in the browser, and the app’s local storage on mobile. Optionality is the design goal here. The local path is the default, and the cloud path is an addition rather than a migration.

The desktop app mirrors the same files to a folder you can open from Finder or Explorer, while the browser and mobile builds keep their storage inside the app sandbox. Either way, the export path is the same verified ZIP, so a backup taken on one platform restores on another.