Regex Tester
Regular expressions are powerful but notoriously difficult to get right. A single misplaced character can mean the difference between a pattern that matches everything and one that matches nothing. Our Regex Tester lets you write a pattern, paste in your test string, and see matches highlighted in real time – making it fast and easy to build, test, and debug your regular expressions.
Why Use Our Regex Tester?
- Real-time visual highlighting shows exactly what your pattern matches.
- Test any regular expression against any text string instantly.
- Useful for SEO filter rules in Google Search Console, Google Analytics, and Tag Manager.
- Ideal for developers validating form inputs, parsing data, and writing server rules.
- Free with no account needed.
How to Use the Tool:
- Enter your regular expression pattern in the regex field.
- Paste your test string in the input area.
- Matches are highlighted in real time as you type.
- Adjust your pattern until it matches exactly what you need.
Regex Tester
Results:
Explanation:
Regular expressions appear throughout SEO and web development – in Google Search Console filters, GA4 regex conditions, Apache and Nginx rewrite rules, robots.txt patterns, form validation, and data processing scripts. Having a reliable tester that gives instant visual feedback dramatically reduces the time spent debugging patterns that don’t behave as expected.
Frequently Asked Questions
What is a regular expression?
A regular expression (regex or regexp) is a sequence of characters that defines a search pattern. It’s used to find, match, and manipulate text based on rules rather than exact strings. For example, the pattern \d{4} matches any four consecutive digits, and [a-z]+ matches one or more lowercase letters.
What regex flavour does this tester use?
The tester uses JavaScript’s native regex engine (ECMAScript regex), which is the same engine used in Google Analytics, most web browsers, and many web-based tools. Regex flavours differ slightly between languages (Python, Java, PHP, etc.) so test in the specific environment where your regex will be used for final validation.
How do I match a literal special character like a dot or bracket?
Special characters in regex (. * + ? ^ $ { } [ ] | ( ) \) have special meanings and need to be escaped with a backslash to match them literally. To match a literal dot, use \. To match a literal bracket, use \[. Our tester highlights what your pattern actually matches so you can immediately see if special characters are being interpreted as literals or as regex operators.
Can I use this for Google Analytics filters?
Yes. GA4 and Universal Analytics both use regex for custom filters, goals, and segments. You can test your regex pattern against sample URL paths or page names here before applying them in Analytics, saving you from accidentally filtering out data you wanted to keep.