Flat keeps a list of the Flatpak apps you always want. On a new machine, open your backup and press Restore: every app goes on, and the ones you have marked Keep settings come back with their profiles, bookmarks and preferences. Changing distribution stops meaning an afternoon of setting things up again.
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Flat has three tabs: All apps, which is everything on this machine; My apps, the list you carry to the next one; and Restore, where it arrives.
All apps lists every Flatpak app on the machine you are leaving, with how much each one keeps. Tick them, or press All, and send them to My apps. There you switch on Keep settings for the ones whose settings matter; the rest install fresh.
Back up saves your list, and the settings of every Keep settings app, into one .fmpack file wherever you choose. It will not start while any of those is open, and it says which. Each app inside is checksummed, so a damaged copy is caught instead of restored.
On the new machine, the Restore tab shows the same list from the backup, with the switch already on for every app whose settings came along. Press Restore and it installs them in one go, then brings those settings back. Anything that goes wrong is named on its own row, and the run carries on to the next app.
Some apps you want as new. Others you want exactly as you left them. Each app on your list gets a switch. An app that has saved nothing says so, so there is nothing to switch on by mistake.
Tick everything on All apps and send it across in one go, or press Add everything here. Or search by name and add apps you do not have yet. Delete one you never want again, and a later "add everything" leaves it out.
Settings are brought back only for apps Restore has just put on. An app already on the machine is left exactly as it is, however the switch is set.
An app restored by hand often opens as if brand new: its folder was copied before it was installed, or while it was running, or with the wrong owner. Flat installs first, closes the app, clears the empty folder the install made, unpacks your data, sets the owner to you, and restores its permissions, in that order.
A single AppImage that runs before anything else is set up on a new machine. It sits in the tray while it works, so a long install can carry on with the window closed, and it keeps itself up to date through one small dot.
A 64-bit (x86_64) Linux desktop with Flatpak installed. Any distribution will do: Flat drives the flatpak command rather than linking against it, and says so plainly if it is missing. If Flathub is not set up yet, Flat offers to add it.
To check Flatpak is there:
flatpak --versionNo. You only need its name. The search box on the My apps tab turns a name into the app's ID, the reverse-web-address name such as org.mozilla.firefox, and that is all Flat needs. The remote is Flathub unless you say otherwise.
Often, not always. Firefox and Thunderbird keep their logins inside their own profile folder, so those generally come back with everything else. Apps that keep their login in the system keyring, GNOME Keyring or KWallet, keep it outside Flatpak altogether, and those need signing in again on the new machine.
Everything in each ticked app's own folder under ~/.var/app, apart from its cache unless you switch caches on, plus the app's permission settings. For a browser that means bookmarks, history, saved passwords and cookies. The file is not encrypted, so keep it somewhere as safe as the machine it came from.
Restore leaves it alone, settings and all: it names it as already there and moves on to the next. Settings are only ever brought back for apps that Restore has just put on, so nothing already set up on a machine is overwritten.
No. Everything Flat installs goes in for your own user, not system-wide, which needs no administrator password and works the same way on every distribution.
They are outside what Flat does. Native .deb and .rpm packages, Snaps and AppImages are not moved or installed.
The small dot beside the version number, top right. Green means up to date and a click checks again. Amber means a newer version is ready: click to download it, watch the white ring fill, and click the blue dot to restart into it. Red means GitHub could not be reached. Flat looks when it starts and every half hour after, but nothing is downloaded until you click.
Mark the file executable (right-click → Properties → “Allow executing” on most desktops), then open it. On a new machine, put your backup file and your saved app list in the same folder as Flat and it finds them both on its own.
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Page last updated: 19 September 2026.