Backup and sync are two different promises
One switch in Sealby covers two related capabilities. iCloud Backup copies your vaults into your own private iCloud as unreadable encrypted blocks, so nothing is lost if a device is. Device Sync goes further: a vault you choose becomes openable on another of your devices, with edits flowing both ways.
They share a switch because sync rides on the backup — but turning backup on does not sync your devices. Syncing is a deliberate second step, and that is the single most useful thing to know before you start: if you enabled backup and your other iPhone still looks empty, nothing is wrong. You have finished step one of four.
Why your vaults can’t just "appear" — and why that’s the feature
Ordinary cloud apps sync everything automatically because they hold an account and a master key that can enumerate all your data. Sealby deliberately holds neither: each vault has its own keys, and there is no list of your vaults anywhere — not on Apple’s servers, not even inside Sealby’s own storage. The same property that means no one can prove how many vaults you have also means the app cannot silently ship them all to a new device.
So setup asks you to do two things an ordinary app never would: pair your devices once, and choose per vault what travels. What reaches iCloud is only sealed blocks of fixed size under random names — nothing that reveals a vault’s name, size, or existence. A vault you have not chosen to sync is, to your other devices, indistinguishable from random noise.
Before you start
You need three things: Sealby Premium (lifetime or an active subscription) — backup and sync are Premium features; the same iCloud account signed in on every device you want to sync; and iCloud Sync & Backup turned on in Settings › App Settings. That is all — there is no Sealby account and no server to sign up for.
Step 1 — Turn on iCloud Sync & Backup
On the device that already has your vaults: Settings › App Settings › iCloud Sync & Backup, and switch it on. Your vaults begin backing up immediately in the background. This alone does not sync your devices — that is what pairing is for.
Step 2 — Pair your devices
Open Sealby on both devices, signed into the same iCloud account. On each, go to Settings › App Settings › Synced Devices › Set up device sync. After the short explainer, each device picks its role on the last screen: the device that already holds your vaults taps "This device has my vaults"; the other taps "This is the new device."
Both screens then show the same 6-digit code. Check they match and confirm on both — the devices reach each other through your private iCloud, which can take up to about thirty seconds. Once paired, each device appears in the other’s Synced Devices list under its hardware model name. The code is a one-time confirmation that expires in minutes, not a password — there is nothing on screen worth photographing.
Step 3 — Choose which vaults sync
Pairing moves nothing by itself. For each vault you want on your other devices: open the vault, go to its settings, and turn on "Sync this vault." Only vaults you switch on ever become openable elsewhere — sync is off by default for every vault, including ones you create later (turn it on for those and they follow your paired devices too, no re-pairing needed).
Step 4 — Open the vault on the other device
On the paired device, enter that vault’s PIN — the same one you already use. The first open may take a moment while the encrypted data finishes downloading; after that it opens like any vault. This first-PIN step is not a formality: it is the no-master-key guarantee at work. A synced vault cannot appear anywhere before you prove you can open it.
Day to day, and the honest limits
Once synced, changes flow both ways — add a file on one device and it appears on the other. Sealby syncs when the app comes to the foreground, when you tap Back up now or Restore from iCloud, and periodically in the background on iOS’s schedule. It is not instant push: changes converge within a foreground or two. If a vault is open when a sync lands, the screen refreshes in place.
The limits, plainly: all synced devices must share one iCloud account (sharing with another person is a different feature); backup must stay on, because sync rides it; and turning sync off is not retroactive — a device that already added the vault keeps it until you remove it there, which the app tells you at the moment you enable sync.
New device, lost device, worst case
Moving to a new iPhone is the everyday path: pair it, switch on the vaults you want, enter each vault’s PIN once. If a device is lost, unpair it from Synced Devices — new vaults stop reaching it. And if you ever lose every device at once, the recovery phrases are the safety net: on a fresh install, each vault’s phrase restores it from your encrypted iCloud backup. One phrase per vault, needed only in the worst case — pairing covers everything else.