First, a quick review of how ad blocking works
(Bear with us. If you're new to custom filters, this is information we want you to know. If you already know what custom filters are, feel free to skip down to "How to add custom filters.")
Nearly all ad blockers, including AdBlock, use rules that tell them what things they should block and hide on web pages you visit. These rules are also known as filters, and they are provided in collections called filter lists. (Our blog post on how ad blockers work goes into greater detail if you're interested in what goes on behind the scenes.)
The filter lists are maintained by volunteers in their spare time. With a few exceptions, the list authors are not affiliated with the developers of ad blockers. For instance, we maintain the AdBlock Custom filter list, but all the other filter lists available in AdBlock are kept up-to-date by others. This is why we have to refer you to the list authors for help when a bad filter breaks a web page or an ad slips through the filter lists. Whenever possible, the list authors will fix the bad filter or adjust the blocking filters and release an update to the filter list, resolving the issue for everyone.
Custom filters enhance and override filter lists
Filter lists block the vast majority of ads on web pages. What they can't block they can usually hide, with some exceptions. But particularly stubborn kinds of ads require more aggressive targeting. In some cases, the filters needed to block them break some functionality on that site, and could even break completely unrelated websites. The list authors are understandably reluctant to include such filters in their lists. Instead, they offer them as "custom" filters―filters you can use to enhance or override the filter lists, customizing your ad blocker for specific websites. Custom filters affect only the people who choose to use them.
Use custom filters with extreme caution
Before we tell you how to add custom filters to your ad blocker, we want you to understand two potential consequences of using them.
Custom filters can break websites.
List authors carefully test new filters before including them in their filter lists. It's impossible to test custom filters that thoroughly on every website. If your custom filters block too much, they can make websites unusable.
Custom filters need a lot of maintenance.
Custom filters may stop working when a website’s design or layout changes or the website changes the way it serves ads to visitors. You will need to keep your custom filters up to date the way list authors do the filter lists.
Where to get custom filters
Most people never need to use custom filters. However, people who like to tweak their browsing experience can use AdBlock to create custom filters very easily. We invite you to read our blog post on how to make the most of AdBlock. As a quick overview, you can use our "blacklist" wizard to block individual ads and other things you don't want to see, and support content creators by whitelisting individual websites and YouTube channels.
One additional source of custom filters is the EasyList forums. That's where the list authors hang out, and where broken websites and unblocked ads are reported. You can search the EasyList forums for the domain name of a website and often find custom filters that have been suggested by the list authors and other volunteers. (The domain name is the main part of a website address. For example, in "serendipity.com," the domain is "serendipity.")
Why can't we just give you some custom filters?
We used to track down custom filters when users reported unblocked ads on particular websites. We kept a library of them in our Knowledge Base to make it easy for other folks to use them, too. Maintaining the library became a nightmare because custom filters change so often.
The bigger problem is that using custom filters can break websites. We don't have the time to verify they do what they're supposed to do, in every browser, without making something else worse. We weren't comfortable with recommending solutions we hadn't tested ourselves. So we stopped giving out custom filters. Our approach now is to point folks to where they can find custom filters on their own.
But just because we can't help you doesn't mean you're out of luck. The folks who hang out in the forums we pointed you to also tend to be happy to help when they're asked nicely.
How to add custom filters
If you use AdBlock to customize web pages, the resulting custom filters are added for you. Here's how to add custom filters you find in the EasyList forums.
- Our AdBlock for Safari Mac app does not yet offer the ability to add custom filters.
- We hope you find this information helpful, but we don't maintain either the filter lists or any custom filters provided in the EasyList forums. If the suggested custom filters don't work, it won't help to report it to us. Instead, please report it as a comment on the forum post where you found them.
- Click the AdBlock button in the browser toolbar and select Options.
- On the CUSTOMIZE tab, click Edit to open the custom filters box.
- Paste the filters exactly as given in the forum post.
- Click Save.
- Reload the web page you're trying to change.
Other ad blockers
- Adblock Plus (ABP): Options > Add your own filters
- µBlock Origin (uBO): Dashboard > My filters
Two final notes
If you have a lot of custom filters, we recommend keeping a copy in a text file somewhere as a backup. Better still, you can turn your custom filters into your own personal filter list.
If adding a custom filter doesn't seem to have an effect, clear your browser cache and cookies to clean up any old data that may be interfering.