Add a filter list
Sval knows more filter lists than its levels use. Under Custom, you can switch any of them on, and add other lists by their address.
You read sites in Swedish and want the Swedish list, or a friend shared a list that blocks a site’s pop-ups.
Switch on a list Sval knows
Section titled “Switch on a list Sval knows”- Open Settings › Privacy and protection.
- Under Ad and tracker blocking, select Customize lists.
- Under Lists, turn on the switch next to the list.
The level becomes Custom, starting from the lists you had. Under Custom, every list has its own switch, so you can skip step 2. The message under the lists offers Undo to go back.
Add a list by its address
Section titled “Add a list by its address”- Open Settings › Privacy and protection.
- Under Ad and tracker blocking, select Add list.
- In List address, paste the list’s address.
- In the menu next to it, choose what the list blocks.
- Select Add.
Sval downloads the list, names it from its title, and keeps it updated. The list shows Added by you.
Details
Section titled “Details”- A list’s address has to start with https://.
- The menu files the list under Ads, Trackers, Annoyances, Scams and malware, Site fixes, or Other.
- Adding a list while on another level switches you to Custom.
- To remove a list you added, select the × at the end of its row. This works under Custom. The message under the lists offers Undo.
- The lists you add sync to your other devices. On each other device, the list waits until you select Allow on this device next to it. Until then, that device doesn’t download it.
- Trust this list lets a list you added run trusted scriptlets, which can set cookies, click buttons, and rewrite responses on any site. Sval asks before it trusts a list. Trust is given on each device and doesn’t sync.
- uBlock Origin’s own lists run trusted scriptlets unless you turn off Use trusted scriptlets from uBlock Origin’s lists and the lists you trust under Advanced.
If something goes wrong
Section titled “If something goes wrong”- Enter a list address starting with https://. Sval only downloads lists over a secure connection.
- Sval already knows this list. Switch it on below. Find it in the lists and turn on its switch.
- That address isn’t a list Sval can add. The address didn’t give Sval a filter list.
Related pages
Section titled “Related pages”© 2026 Ellm Tree, Inc. Sval is not officially associated with Mozilla or its products. Firefox is a trademark of the Mozilla Foundation in the US and other countries.