Private browsers with extension support profiles and encrypted sync

The strongest options are Firefox, Brave, and Vivaldi. All three support browser extensions, separate browsing profiles or equivalent isolation features, and encrypted cross-device syncing. The important distinction is whether you can keep work and personal data separate while also syncing bookmarks and history securely.

Best private browsers for your requirements

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1. Mozilla Firefox

(Best for profile separation)

Firefox supports extensions, independent browser profiles, and Firefox Sync with end-to-end encryption. Sync can include bookmarks, history, and add-ons.www.firefox.com+2

• Profiles: Yes; separate profiles can keep different browsing environments apart.
• Extensions: Yes, with some differences on mobile.
• Encrypted sync: Bookmarks, history, and add-ons.
• Watch out: Each profile needs its own sync configuration if you want separate data sets; don't assume profiles automatically share or isolate synced data in every configuration.
• Firefox ·Firefox Sync setup

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2. Brave

(Best for built-in privacy)

Brave combines tracker and ad blocking with Chrome Web Store extension compatibility and client-side encrypted Sync. Its Sync system supports bookmarks, history, and extensions.brave.com+2

• Profiles: Yes, desktop supports separate browser profiles.
• Extensions: Broad Chromium extension support.
• Encrypted sync: Yes, including bookmarks and history.
• Watch out: Configure and verify each profile's Sync setup separately; don't assume that all profiles share one sync chain.
• Brave ·Brave privacy features

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3. Vivaldi

Vivaldi is a strong fit if you want extensive customization. Its built-in Sync supports bookmarks, history, extensions, and other browser data, with end-to-end encryption using a password that isn't sent to Vivaldi.www.firefox.com+4

• Profiles: Yes; separate profiles require separate Vivaldi accounts for profile syncing.
• Extensions: Compatible with Chromium extensions.
• Encrypted sync: Yes, including bookmarks and history.
• Watch out: Separate accounts for separate profiles can make managing several environments less convenient.
• Vivaldi ·Vivaldi Sync documentation

Comparison at a glance

Sources: official Mozilla, Brave, and Vivaldi documentation.www.mozilla.org+3

What about Tor and other privacy browsers?

• Tor Browser: Excellent for anonymity, but deliberately does not sync your browsing activity or cloud-back up your identity. Not a match for your full requirements.www.torproject.org+1
• Mullvad Browser: Worth considering for anti-tracking and fingerprinting protection, but not as a built-in encrypted history-and-bookmark sync solution.
• Norton Private Browser: Offers end-to-end encrypted bookmark and history sync, but I would verify its profile separation and extension-management capabilities before choosing it for your full setup.support.norton.com

My recommendation

I'd start with Firefox if you want strong separation between work, personal, and research browsing, or Brave if you prioritize out-of-the-box tracker blocking.

One important distinction: encrypted sync protects data in transit and on the sync server; it doesn't automatically make data private from other people who can access your unlocked browser profile. For maximum separation, use distinct profiles and configure sync independently for each one.

One question that would help narrow this down: Do you want to sync across Windows/macOS/Linux computers only, or between computers and Android/iPhone too? Mobile support can change which option is best.

Finding a privacy-focused browser that hits all four requirements—extension support, native separate profiles, end-to-end encrypted (E2EE) bookmark/history sync, and multi-device capability—is a specific balancing act. Most traditional browsers do encryption, but privacy-oriented ones handle profiles or history syncing differently.

The primary options that support these criteria, along with how they achieve them, include:

• Firefox (or LibreWolf/Mullvad-adjacent setups via standard Firefox)
  • Extensions: Full support via Mozilla Add-ons.
  • Separate Profiles: Excellent built-in desktop profile manager (about:profiles ), or lightweight isolation via Multi-Account Containers.
  • Encrypted Sync: Uses true end-to-end encryption via a Mozilla Account (your password derives the local encryption key, so Mozilla never sees your unencrypted data).
  • Cross-Device Sync: Syncs bookmarks, history, extensions list, and passwords seamlessly. Note: To keep separate profiles isolated across devices, you must map each separate local profile to a unique/separate Mozilla Account.support.mozilla.org+3
• Vivaldi
  • Extensions: Full support for Chrome Web Store extensions (Chromium-based).
  • Separate Profiles: Robust native profile creation directly from the UI menu to completely split user data.
  • Encrypted Sync: Uses end-to-end encryption protected by a user-created sync password/phrase that never hits their servers.
  • Cross-Device Sync: Syncs history, bookmarks, passwords, and notes. To sync distinct profiles separately across devices, you simply log each distinct profile into a separate Vivaldi Account.help.vivaldi.com+2
• Brave
  • Extensions: Full Chrome Web Store extension compatibility.
  • Separate Profiles: Native profile switcher allowing fully isolated local browsing environments.
  • Encrypted Sync: Uses a client-side encrypted sync chain.
  • Cross-Device Sync: Syncs bookmarks, history, and settings across a custom QR/code-phrase sync chain. Caveat: Brave’s sync chain links devices rather than separate profile accounts natively; syncing multiple distinct profiles requires pairing individual sync chains per profile, which can get cumbersome.youtube.com+2

Would you like help setting up end-to-end encrypted sync for Firefox or Vivaldi , or do you want to explore which browser has the best anti-fingerprinting posture for your threat model?

Finding a browser that checks all four of your boxes—privacy-focused, extension support, separate user profiles , and end-to-end encrypted (E2EE) sync —requires balancing traditional convenience with strict zero-knowledge architectures.

The top options that successfully thread this needle are outlined below:

1. Mozilla Firefox (Hardened with Containers)
   • Privacy: Excellent when adjusted. It features Total Cookie Protection and strict tracking protection. Mozilla’s sync is fully end-to-end encrypted using your master password/account key so they cannot read your data.
   • Extensions: Full support for standard desktop extensions (via Firefox Add-ons ), including uBlock Origin.
   • Profiles & Containers: Instead of entirely separate heavy-weight profiles, Firefox uses Multi-Account Containers , which isolate cookies and storage per tab (e.g., keeping personal and work logins separate in the same window). If you need completely isolated multi-user profiles with distinct extension sets and histories, Firefox also supports native separate profile management via about:profiles.
   • Sync: E2EE sync covers bookmarks, history, passwords, and container configurations.
   • Note: Requires minor privacy tweaks out of the box (like turning off telemetry).reddit.com+2
2. Brave Browser
   • Privacy: Strong out-of-the-box blocking of trackers, ads, and fingerprinting scripts via Brave Shields.
   • Extensions: Full support for Chrome-based extensions (via the Chrome Web Store).
   • Profiles: Robust, native multi-profile support allowing completely separate windows, histories, and extension preferences per user profile.
   • Sync: Uses a decentralized Brave Sync Chain secured by client-side, zero-access end-to-end encryption using a pass-phrase/sync code that only you control. Data never touches third-party cloud servers unencrypted.
   • Note: It is Chromium-based, which is a downside for some strict privacy purists who prefer non-Blink/non-Google engines, but it strips out Google telemetry.pcmag.com+2
3. Vivaldi
   • Privacy: Highly customizable with built-in ad and tracker blockers. Vivaldi has a strict privacy policy and stands out for using end-to-end encryption specifically for its sync infrastructure (bookmarks, history, passwords, and settings are encrypted client-side before syncing to their servers).
   • Extensions: Full Chrome Web Store extension support.
   • Profiles: Excellent native user profile manager, letting you isolate different users/workflows completely.
   • Sync: E2EE sync protected by a user-generated encryption password.
   • Note: Like Brave, it is Chromium-based.pcmag.com

Summary Comparison

• Choose Firefox if you want a non-Chromium engine and prefer lightweight tab containers or native profiles backed by Mozilla's E2EE sync.blog.mozilla.org+1
• Choose Brave if you want a fast Chromium option with aggressive out-of-the-box tracker blocking and a zero-knowledge sync chain.brave.com+1
• Choose Vivaldi if you prioritize deep interface customizability, native profiles, and explicit E2EE syncing for your history and bookmarks.pcmag.com

Would you prefer a non-Chromium engine (Firefox-based) or do you mind a Chromium-based browser like Brave or Vivaldi? I can narrow down the installation and hardening steps for whichever path you prefer.

If you want a privacy-focused browser that supports extensions, keeps different parts of your digital life in separate profiles, and syncs bookmarks and browsing history with end-to-end encryption (E2EE), I'd start with Firefox and Vivaldi. Brave is also worth considering, especially if you want strong built-in ad and tracker blocking.

The key distinction is that encrypted sync and profile separation are two different features. A browser might encrypt your synced data but still make it awkward to maintain separate personal, work, and research environments.

The best options at a glance

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1. Mozilla Firefox

(Best overall for privacy)

Firefox supports browser extensions, independent user profiles, and E2EE sync for bookmarks, history, and other selected data. Mozilla says it cannot decrypt your synced browsing data.support.mozilla.org+1

Main caveat: each profile is separate, and Mozilla advises using a separate Mozilla account for each profile if you want to back up and sync them independently.

Best for: privacy, flexible extensions, and strong separation between identities.

Firefox ·Profile management

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2. Vivaldi

(Best for customization)

Vivaldi supports Chrome-compatible extensions, user profiles, and E2EE sync for bookmarks, history, extensions, settings, and more. You choose an encryption password that is not sent to Vivaldi.help.vivaldi.com+1

Main caveat: each profile needs its own Vivaldi account to sync profile data independently.

Best for: power users who want extensive customization and granular browser organization.

Vivaldi ·Sync documentation

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3. Brave

Brave combines built-in ad and tracker blocking with Chromium extensions and client-side encrypted sync. It supports syncing bookmarks, history, extensions, and other selected data.brave.com+2

Main caveat: its sync setup uses a device sync chain, and its profile-sync workflow is less straightforward than simply having a separate sync account for each Firefox profile.

Best for: strong out-of-the-box tracking protection with a Chrome-like extension ecosystem.

Brave ·Sync documentation

Feature comparison

Sources: Mozilla'sSync and profile documentation