Is Firefox encrypted?
Yes. Only you can read the bookmarks, history, passwords and tabs Firefox Sync stores, because they're sealed before they leave your browser. Firefox also tries a secure connection to every site first.
Checked on 25 October 2026 against 3 sources.
Made by Secria. We grade every app by the same rules. How we check
- Connection to sitesOnly you and the siteSince Firefox 136 for computers, Firefox loads pages over a secure connection when it can and falls back only if a site has none.3
- Saved passwordsOnly youSealed in your browser before it syncs, and Mozilla says it can't decrypt it.1, 2
- History and open tabsOnly youHistory and open tabs are sealed the same way.1
- BookmarksOnly youBookmarks are sealed the same way.1
- Who holds the keys
- Your devices, using a key made from your Mozilla account password. Mozilla never has it.
- What Mozilla can still see
- Your email address, how many devices you sync and what kinds, and technical details like your browser version and rough location from your IP address.
Email is worth checking next: Gmail, Outlook and iCloud Mail can all read your mailbox. See which email services can.
Is Firefox Sync end-to-end encrypted?
Yes. Mozilla's privacy notice says your synced data is encrypted before it leaves your browser, and only another browser on your sync account can decrypt it1. That covers tabs, passwords, bookmarks, history, add-ons, saved form details and settings1.
The key is made from your account password on your own device, and Mozilla says that key never leaves it2.
Can Mozilla see my Firefox passwords?
No. Mozilla says it can't decrypt anything you sync1. What it does keep is your email address and some details about your devices, like how many you have and what kinds, so you can spot and remove one you don't recognize1, 2.
Does Firefox use HTTPS by default?
Yes. Since version 136 for computers, released in March 2025, Firefox tries to load every page over a secure connection first3. If a site doesn't offer one, Firefox falls back to an unsecured connection so the page still opens3.
How Firefox compares
Sorted by how many parts are sealed by default, then by how many can be. Ties go A to Z.
Sources
- Mozilla Accounts Privacy Notice, Mozilla. Read on 25 Oct 2026.
- Private by Design: How we built Firefox Sync, Mozilla. Read on 25 Oct 2026.
- Firefox 136.0 release notes, Mozilla. Read on 25 Oct 2026.
Changes to this answer
- First published.