How to Enable Firefox Sync for Backup

Firefox Sync keeps a copy of your bookmarks, passwords, history, and open tabs on Mozilla's servers, ready to restore on a new computer or browser profile. Turning it on only takes a free Mozilla account and a few clicks in the hamburger menu.

You'll also choose which data gets backed up, pair a second device, and confirm that the backup is actually moving.

In this guide, I have covered:

Why enable Firefox Sync for backup

If you use Firefox on a computer, a wiped profile or a new machine can take bookmarks, saved passwords, and settings with it. Firefox Sync keeps a running copy of those items, plus history, open tabs, add-ons, preferences, and autofill data, on Mozilla’s servers.

When you sign in on another computer or after a clean reinstall, Firefox pushes that data back automatically. That makes Sync a real backup route, not just a sync convenience.

Create or sign in to a Mozilla account

Before Sync can store anything, you need a free Mozilla account tied to your email. If you already have one from another device, use the same credentials.

1. Open accounts.firefox.com in any browser.
2. Click Create an account and enter an email and password, or click Sign in if you already have one.
3. Confirm the verification link Mozilla emails to your inbox.

Once the email is confirmed, return to Firefox on your computer to finish connecting Sync.

Enable Firefox Sync from the hamburger menu

Once your Mozilla account is confirmed, the fastest way to turn Sync on is straight from the Firefox menu bar. You do not need to dig into Settings first.

1. Click the hamburger menu in the top-right corner of Firefox.
2. Click Sync and save data near the top of the menu.
3. Click the Sign in button next to it.
4. Type the email address for your Mozilla account into the email field.
5. Click Next.
6. Type your Mozilla account password into the password field.
7. Click Sign in.
8. Click Finish on the confirmation screen.

You should now see your account email and avatar in the menu instead of the Sign in button. That swap is the quickest signal that Sync is connected.

Choose what Firefox Sync backs up

With Sync connected, Firefox defaults to backing up bookmarks, history, open tabs, logins and passwords, add-ons and themes, preferences, credit cards, and addresses.

You can trim that list if you only want certain data to leave the computer. If your main reason for enabling Sync is to protect saved logins, our guide to managing passwords in Firefox on the computer covers the password manager side in more detail.

1. Click the hamburger menu and choose Settings.
2. In the left-hand panel, click the Sync tab.
3. In the Manage what Sync backs up section, click Change….
4. Tick or untick each category you want synced: Bookmarks, History, Open tabs, Logins and passwords, Add-ons and themes, Preferences, Credit cards, and Addresses.
5. Click Save changes to apply.

Any category you untick stops being uploaded on the next sync. Data that was already on Mozilla’s servers is removed within a short window after you save changes.

Add a second device to your Sync account

Backing up only matters if you can restore. Pairing a second device turns Sync from a one-way backup into a two-way pool across your devices.

On the computer that is already signed in:

1. Click the hamburger menu and pick Sync and save data.
2. Click Manage devices (or Connect another device).
3. Click Show QR code so the computer displays a pairing page at firefox.com/pair.

On your phone (Firefox for Android or iPhone):

1. Open Firefox and tap the hamburger menu .
2. Tap Sync and save data.
3. Tap Ready to Scan and point the camera at the QR code on your computer screen.
4. Approve the new device on both sides when prompted.

If scanning does not work, tap Use email instead on the phone and sign in with the same Mozilla account. The new device appears under your account within a few seconds.

Confirm Sync is working

Sync runs in the background. The easiest way to check it is alive is to add something small and watch it appear on another signed-in device.

1. Save a placeholder bookmark such as Sync test on the computer.
2. On the second signed-in device, open the Bookmarks menu and look for Sync test.
3. If the bookmark appears within a minute or two, Sync is moving in both directions.

You can also open Settings and click the Sync tab to check the connection. The top of the page shows the email address of the connected account and the timestamp of the last successful sync. If that timestamp updates after you make a change, the backup path is alive.

What to do if Firefox Sync will not turn on

If the Sign in button does nothing, or you keep getting stuck on a loading spinner, work through these in order.

1. Make sure Firefox is up to date. Open the hamburger menu and pick Help, then About Firefox. If an update is ready, restart to apply it.
2. Check that your computer’s date and time are correct. A clock that is far off will break the secure connection to Mozilla’s servers.
3. Sign out and back in. Open the hamburger menu , choose Sync and save data, click Sign out, then sign back in with the same Mozilla account.
4. Try a private window. If Sync signs in there but not in a normal window, an extension is interfering. Disable extensions temporarily and try again.
5. Reset the Sync state. Open about:sync in the address bar and click Reset next to Reset Sync. Sign in again from the hamburger menu.

TIP: If nothing above helps, signing in on a different network (such as a phone hotspot) tells you whether your current network or firewall is blocking Mozilla’s Sync servers.

RELATED: Enable and Sync Data in Firefox browser between Devices