5 Firefox Extensions That Respect Your Privacy (No Accounts, No Cloud)

Most browser extensions require an account. Some sync your data to a cloud server. A few are upfront about this — many aren't.

Here are 5 Firefox extensions that work entirely offline, store nothing remotely, and require zero account setup.

1. Tab Manager & Session Saver

Tab Manager & Session Saver saves named sessions of your open tabs entirely in browser.storage.local. No sync, no accounts, no network requests beyond loading the extension itself.

What it does: You name the current session, close the tabs, and restore them later with one click. Useful for separating work contexts without needing a cloud backup.

2. NightOwl

NightOwl forces dark mode on any site using CSS inversion. Per-domain settings are stored in browser.storage.local.

No account, no telemetry, no external calls. It's just CSS being injected at the browser level.

3. uBlock Origin

The standard for content blocking. Runs entirely locally with filter lists stored on your device. The filter lists download over HTTPS but nothing about your browsing is sent anywhere.

Available at: addons.mozilla.org/en-US/firefox/addon/ublock-origin/

4. Firefox Multi-Account Containers

Mozilla's own extension for isolating different websites into separate cookie jars. Your social media cookies don't touch your banking cookies.

Available at: addons.mozilla.org/en-US/firefox/addon/multi-account-containers/

5. Bitwarden

Technically requires an account (for password sync across devices), but you can run it entirely self-hosted. Passwords are encrypted before leaving your device, and the source code is open.

Available at: addons.mozilla.org/en-US/firefox/addon/bitwarden-password-manager/

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What to Look For

Before installing any extension, check the "Permissions" section on the AMO listing. Extensions that need "Access your data for all websites" and also want "storage" and network access deserve extra scrutiny. The most privacy-respecting ones do exactly what they advertise using the minimum permissions needed.

For open-source extensions, you can verify what the code actually does vs. what the description says. All of the above have public source code or are developed by organizations with public audit histories.