Privacy and protection

Settings › Privacy and protection holds the settings that apply to every site. Choices for one site are made with the controls in the address bar, and listed in Settings › Sites.

Address bar site controls covers the Privacy and Security button and the site settings menu.
Settings › Sites covers the defaults for every site and each site’s own page.

Ad and tracker blocking

Sval blocks ads and trackers with filter lists. Changes apply the next time a page loads.

Level chooses the lists Sval uses.
- No Blocking blocks nothing.
- Balanced Blocking blocks ads and trackers with lists that rarely break sites. It’s the level a new install starts on.
- Strict Blocking adds lists that block more, including trackers in links, social widgets, and scam sites. Some sites might break. It also strips tracking parameters from the addresses you open.
- Custom lets you pick any of the lists Sval knows, and add your own by address. It starts from the lists of the level you were on.
Lists shows the lists in use, grouped by what they block: Ads, Trackers, Annoyances, Scams and malware, Site fixes, and Other. Each list names its license or its address. Under Custom, each list has a switch.
Add list adds a list by its address. Adding one switches the level to Custom.
Customize lists switches to Custom, starting from the level’s lists.
Trust this list shows on a list you added. It lets the list run trusted scriptlets, after you confirm.
Allow on this device shows on a list you added on another device. The list downloads here only once you allow it.
Allowed domains lists the domains Sval never blocks, at any level. Add domain adds one.

The level, the lists, and the allowed domains sync to your other devices.

Advanced

My filters holds your own rules, one per line, in uBlock Origin’s syntax. Save saves them. They sync to your other devices.
Let My filters use trusted scriptlets lets your own rules run trusted scriptlets, after you confirm. It applies to the rules as you trusted them on this device.
Hide page elements and apply site fixes from the lists is on by default.
Use trusted scriptlets from uBlock Origin’s lists and the lists you trust is on by default.

Cookies and site data

Cookies chooses which cookies sites may set: Allow every cookie, Keep each site’s cookies to that site, Block cookies from trackers, Block cookies from sites you haven’t visited, Block cookies from other sites, or Block every cookie. It starts on Keep each site’s cookies to that site.
The size line says how much space site data and the cache take.
Clear browsing data, Clear data for specific sites, and Manage exceptions open Firefox’s own dialogs for them.
Clear cookies and site data every time you close Sval clears them on every quit.

Fingerprinting

These settings control what sites can learn about your browser and device. Sval’s defaults make you look like other Sval users and rarely break sites. Changes apply the next time a page loads.

Fingerprinting protection applies In every window, Only in private windows, or Off. It starts on In every window.
Strict fingerprinting protection turns on every strict item, which protects you more and breaks more sites. It’s off at first. Its line says how many strict items are on.
Restore Sval’s defaults puts every fingerprinting setting back, with Undo in the message that follows.
Under Language and region, Tell sites all your languages is off, so sites see only your first language.
Under Hardware and devices, Report the real CPU core count is off, so each site sees its own count, between half your cores and all of them.
Under Network, WebRTC (calls in the browser) is Allow calls, Only through your proxy, or Block. Allow calls is the default, and sites don’t see your local network address.

Advanced

Advanced lists each protection by group: Graphics, Fonts and text, Appearance, Screen and window, Audio, video, and media, Language and region, Hardware and devices, Timing, Network, and Compatibility. Each group shows how many of its protections are on. Each protection says what it hides and what it can break, and is marked when it differs from Sval’s default.

Under Compatibility, Mozilla’s compatibility fixes is off by default. Turned on, it weakens protection on Google’s and Bing’s sites, following a list Mozilla publishes.

Privacy signals

Global Privacy Control tells sites not to sell or share your data. In some places the law requires them to honor it. It’s on by default.
Under Advanced, Do Not Track asks sites not to track you. Nothing requires them to honor it. It’s off by default.

HTTPS-Only Mode

Firefox’s own setting. It allows only secure connections to websites, and asks before connecting insecurely: Enable HTTPS-Only Mode in all windows, Enable HTTPS-Only Mode in private windows only, or Don’t enable HTTPS-Only Mode, which is the default. Manage Exceptions… lists the sites you let load insecurely.

Secure DNS

This setting controls how Sval looks up the sites you visit. It applies to every site and syncs to your other devices.

Your network’s DNS is the default. It works with internal names, VPNs, and router filters. Your network can see the sites you look up.
Encrypted, with fallback looks sites up through the resolver, and through your network’s DNS when that fails.
Encrypted only looks sites up only through the resolver. If it can’t be reached, sites don’t load.
Choose provider: offers Quad9, the default, Cloudflare, and Custom, which takes another resolver’s address. It shows with the encrypted choices.
Internal names lists domains that always use your network’s DNS.

Data breach warnings

Warn about sites with a data breach in the last year is on by default. Sval checks sites against Have I Been Pwned’s list of breaches, downloaded from Mozilla. When this is off, Sval doesn’t download the list.

Deceptive content and dangerous software protection

Firefox’s own setting. Block dangerous and deceptive content is on by default, with Block dangerous downloads and Warn you about unwanted and uncommon software under it.

Password manager and Security keys

See Passwords.

History

Firefox’s own setting: Remember history, Customize history, or Never remember history.

Advanced

Under More tracking protection:
- Strip tracking parameters from the addresses you open is on with Strict Blocking, and off otherwise.
- Block redirect tracking is off by default.
- Never send a page’s full address to the next site you go to is off by default.
Under Bookmarklets, Run bookmarklets from Favorites is on by default.
Certificates and Proxy settings are Firefox’s own settings.