Sync — your books on every device

JustWrite keeps your books on each of your computers and on your phone, and sync carries your changes between them. Every device works with no network at all — sync catches it up the next time it can reach another device. Nothing ever asks you to choose between two versions: if you add a paragraph on one device and fix a typo in the same scene on another, both survive.

You’ll find it in Settings → Sync.

What syncs: your books — the manuscript, the story bible, images and saved versions. What stays on each device: settings, AI providers and keys, writing statistics and the search index.

---

Pick the way that suits you

Way	When	What you do
Cloud folder	anywhere; the other computer can be off	On each computer, choose the same folder inside Dropbox, OneDrive or another sync app.
Pairing	same Wi-Fi, or over Tailscale / ZeroTier	Turn on Let my other devices connect on one computer, then pair the other with its code.
By hand	no network, no accounts	Export a file, carry it over (email, a USB stick, anything), import it on the other device.

You can use more than one: a cloud folder for everyday work and a file by hand when you’re away from both.

---

Your devices

This device shows the name your other devices see (it starts as your computer’s name — change it to something like “Study laptop”), and how often JustWrite syncs on its own while it’s open (every 5 minutes unless you change it; 0 means only when you press Sync now).

The line at the top tells you when this device last synced, and with which device — for example “Synced 2 min ago · from Study laptop”. Devices lists every device this one has synced with, and how: by hand, the cloud folder, or the network.

---

A cloud folder

1. On your first computer: Settings → Sync → Cloud folder → Choose folder…, and pick a folder inside your Dropbox or OneDrive (for example Dropbox/JustWrite).
2. Pair your second computer with the first (see Pairing below) — that gives it the library’s key. If the first computer is off, pairing still works: the second one joins with the code and the folder carries the changes.
3. On the second computer, choose the same folder.

Each device writes only its own files into the folder, and they’re encrypted with your library’s key, so the folder’s contents are unreadable to anyone without it. Dropbox or OneDrive moves the files; JustWrite reads them shortly after it starts, every few minutes while it’s open, and when you press Sync now.

Your live database never goes into the cloud folder — only these change files do, which is why two computers can’t corrupt each other through it.

If the folder you choose already holds another library, JustWrite tells you which devices it comes from: pair with a code from one of them first, so your books join that library instead of starting a second one beside it.

---

Pairing

On the computer that has your books:

1. Settings → Sync → Other devices: turn on Let my other devices connect. JustWrite then accepts connections from your other devices — restart it once for this to take effect, and allow it through Windows Firewall when Windows asks.
2. Press Show pairing code. You get a QR code and the same code as text.

On the other device: Settings → Sync → Pair with a code, paste the code, press Pair. The two sync at once, and again every few minutes while both are open.

The code carries your library’s key and a password for this computer — share it only with your own devices.

Over the internet: Tailscale or ZeroTier

Pairing works across the same Wi-Fi out of the box. To pair a device that’s somewhere else (your laptop at home, you at a café), install Tailscale or ZeroTier on both devices and sign in to the same account. They give each device a private address that works from anywhere; JustWrite’s pairing code includes that address when one is present. Nothing else to set up — your devices then talk to each other directly, encrypted by Tailscale or ZeroTier.

Without Dropbox or OneDrive: Syncthing

Syncthing keeps a folder the same on several devices with no cloud account at all. Point it at a folder, then choose that folder as JustWrite’s cloud folder on each computer. (Android only among phones, for now.)

---

By hand

1. Settings → Sync → By hand. The books you changed since your last export are already ticked.
2. Optional: tick Encrypt the file with this library’s key if the file will travel somewhere you don’t trust.
3. Export… saves a .jwsync file. Send it any way you like.
4. On the other device: Import… and pick the file. It merges — importing the same file twice, or an older one, changes nothing that’s newer.

If the file comes from a device that hasn’t synced with this one before, JustWrite asks whether to join that device’s library. Say yes, and your books on both devices become one library from then on.

---

On your phone

JustWrite on a phone keeps your books in the app itself and works with no network, like a computer. What it does there: the books — the manuscript, the story bible, images and saved versions — sync, and the AI features that use an online provider. What stays on a computer: the local AI engine and the book search by meaning. To use the AI there, open the AI page, add an online provider with its Default model, then press Set as default on it; until you have, an AI feature says “No AI model is set up on this phone…” with those steps.

The screens. The phone shows the same pages as a computer, laid out in one column. The sidebar opens from ☰ at the top left and closes when you pick a page; the title bar keeps Back, the book’s title, Undo, Redo, the AI status and Search (Forward and the theme pickers stay on the computer — Settings → Appearance has the theme and light/dark). A page’s buttons sit on the row under its title. A table wider than the screen scrolls sideways with its first column kept in view, and its pager keeps the count, the ‹ › arrows and the page size; the plot board, the cast-presence heatmap and the writing calendar on Analysis scroll sideways inside their own box. In the editor the formatting toolbar wraps onto several rows above the text. A dialog’s AI chip sits on its own row under the dialog’s title. Settings leaves out Backups, Storage, Server and Logs, which belong to a computer.

Getting your books onto the phone. On a new phone the welcome screen says Your books are on another device? Sync them here. On your computer open Settings → Sync → Other devices, turn on Let my other devices connect (restart JustWrite once), and press Show pairing code. On the phone press Scan code… and point the camera at the QR code — or paste the code’s text and press Pair. The books arrive and the newest opens. (The first scan asks to let JustWrite use the camera; pasting the code needs no camera.)

After that the phone syncs with the computer shortly after it starts, every few minutes while it’s open, and when you press Sync now — whenever the two can reach each other (the same Wi-Fi, or Tailscale / ZeroTier when you’re away). Other devices can’t reach a phone; it reaches out to your computer.

By hand works on the phone too: Export… hands the file to the phone’s share sheet (save it to Files or Drive, send it by mail), and Import… opens a file you received.

A cloud folder (OneDrive, Dropbox) isn’t available on the phone yet — it needs signing in to them.

If the phone’s storage is cleared. A phone may clear an app’s web storage when it runs short of space. JustWrite also keeps a copy of your changes in its own app files, and if it ever starts with an empty library, it rebuilds your books from that copy.

Good to know

• Resetting the workspace starts a new library on this device — pair your other devices with it again.
• Restoring a backup puts this device back where the backup was, and the backup keeps its own age: the next sync brings back what was changed, made or deleted since — on your other devices, and what this device had already synced to them — and your other devices keep their newer work. What this device changed after the backup and never synced is gone, as it would be without sync.
  • After a restore, this device carries on in sync as a new device: your other devices’ Devices list it as a new entry beside the old one (both with its name), and the old one’s files stay in the cloud folder. In this device’s own Devices, the old entry reads ‹name› (before the restore on ‹date›). There is no Remove: that entry’s cloud-folder copy is how this device gets its newer work back, and a device that is still offline may not have read it yet.
  • This device keeps its own sync settings — the cloud folder, the paired devices and the passwords they reach it with, the library key and its name — not the ones in the backup.
  • While this device is syncing (a cloud folder or a paired device is set), a backup from another sync library — made on a device that wasn’t synced with this one — is refused with “This backup is from another sync library. Stop using the cloud folder and remove your paired devices in Settings → Sync, then restore it.” A device that isn’t syncing restores it and stays in its own library.
• Sync isn’t a backup. A deleted chapter is deleted everywhere. Keep using Backups.
• Sync needs JustWrite open on the devices taking part; the cloud folder lets them take turns.
• Changes from another device show up by themselves — but not while you’re typing or a dialog is open. They wait until you click out of the text, so nothing you’re in the middle of is lost.