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Using regex to block URLs
Using regex to block URLs
Updated over a week ago

This tutorial explains how 1Blocker helps block URLs both efficiently and flexibly. The article is worth reading if you want to dive into one of the most powerful features of 1Blocker.

However, if you find this material difficult, you can start right from the beginning: Block Sites - we've prepared several articles that give a brief overview of how to create basic custom rules in the Basic Tips section.

Important: the following rule format is valid only for the 'Block URL' type of rules available in the Advanced Customization section.

While blocking URLs, 1Blocker takes advantage of regular expression patterns or regex. A regular expression represents a sequence of characters written in a special format. Regex patterns are widely used, as they help engines extract information from any text by searching for one or more matches of a specific pattern. In our case, the engine is called WebKit's content blocker - the Safari's engine that processes the rules, and the patterns are represented by any URLs which we want to block.

Let’s now see how they work.

In regex, every character is “encoded” and validated symbol by symbol from left to right. We can divide regex characters into two groups:

  • ordinary characters like letters, digits, and some symbols. When Safari's engine meets an ordinary character, it perceives such a character as it is, without changing its function. For example, a regex “blocker” is the most basic pattern, simply matching the literal word “blocker”.
    special characters, this is where the great power of regex lies. Some regex characters make the engine act in a special way, and they make the searching possibilities more flexible. For example, a dot . matches any character, so that three dots may mean: dog, cat, run, one, etc. The following characters are special:

    • . - a dot

    • [] - square brackets

    • () - parentheses

    • ? - a question mark

    • * - an asterisk

    • + - a plus

    • ^ - a caret

Also, there is an important rule you should remember about special characters. If a URL contains one of them, such a symbol must be escaped with a backslash \.

For example, let’s try to block the following URL:

There is a dot before “com”, right? So the engine will think that there is a character before the “com” part and it might be any symbol, not just a dot. So, we need to put a backslash before the dot to match it literally: https://domain\.com, so that WebKit will clearly see that it is literally the dot before the “com” part.

Special Characters

If the main idea of regular expressions is a bit clearer now, let’s take a closer look at every special character supported by our engine. Important: these features apply only while creating rules in the Expert editor (available on Premium, learn more: Going Premium).

  • . (dot) can match any single character (letter, digit, whitespace, anything). If you actually need a dot in a URL, don’t forget to escape it with \.

For instance, https://1bl.cker\.com will block not only, but also,, etc.

  • [a-c], [abc] or any set of characters inside [square brackets] will only match any combinations of given characters [abc] or a sequential range of characters [a-c] and nothing else. In other words, the rule will be triggered only if any of the characters given in square brackets are found in the corresponding place in the URL.

A couple of examples: the pattern https://1blocker\.[kc]om corresponds either to https://1blocker.сom or https://1blocker.kom.

And speaking of ranges of characters, https://[1-3]blocker\.com will match three websites,,, and

  • + represents either 1 or more of the character that it follows (it always follows a character or a group of characters).

For instance, we have the following pattern https://1blo+cker\.сom. It will match https://1blocker.сom, 1blooocker.сom,, and so on ad infinitum.

  • * represents either zero or more of the character that it follows (it also follows a character or a group of characters). So, as it may represent zero characters, there might be nothing in the corresponding position in the URL.

This example https://1blo*ck*r\.сom matches such URLs as https://1blckr.сom, https://1blocker.сom, https://1blooockeer.сom, and so on.

  • ? allows you to match either zero or one of the preceding character or group of characters. In other words, it denotes optionality. You can use it in any pattern to match both http and https versions of the same website.

So the pattern https?://domain.сom will block both and https://domain.сom.

  • (abc) can capture any subpattern inside of a pair of parentheses as a group, which means that we can apply other special symbols, e.g., +, * or ? to the whole group.

Let’s take a look at this pattern: https://(.*\.)?domain\.com. It will block not only but its subdomains consisting of any number of characters as well, for instance, Let's break down the pattern. Here we have a group marked by (). The whole group is optional because of ?, and the group itself consists of any number (*) of any characters (.) and an escaped dot \.

  • ^ a caret at the beginning of a pattern restricts the URL to start only with the character that follows the caret(^). Also, a caret inside square brackets tells the engine to match all characters except the ones inside given square brackets.

Here are the examples for both cases:

this pattern ^https://domain\.com will make sure that nothing precedes the letter h, it must be the first character of the string. So, if the target URL is a part of another URL, the rule won’t work:

And an example using caret in square brackets [ ], the pattern https://[^d]omain\.com won’t match, but will work for,, etc.

Useful Templates

We would like to give you two basic patterns you can apply to create effective custom blocking rules.

The first one matches any URLs, no matter what characters it contains or their total number.


And here's the pattern that Apple recommends using to block regular domains, as it blocks subdomains and is balanced enough, so you are less likely to see any side effects.


Let’s break it down into smaller parts:

  • ^https?://+ matches http:// and https:// and makes sure that there is no text before the URL;

  • ([^:/]+\.)? targets all subdomains if there are any;

  • domain\.com matches the domain itself;

  • [:/] this tiny part blocks the domain even if the URL contains an extra part after .com. For example, or

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