Definition
Regular expressions (regex) are an essential tool for advanced technical SEO. They allow you to filter URLs in Search Console, create complex redirect rules in .htaccess, segment traffic in Google Analytics, extract data with Screaming Frog, and analyze server logs. Regex use a special syntax: . (any character), * (repetition), ^ (start), $ (end), | (or), [] (character class), () (groups). In SEO, common use cases include: filtering URLs with parameters (?.*=), identifying non-compliant URLs, creating dynamic redirects (RewriteRule), and segmenting reports by page type. Mastering regex is what separates a beginner technical SEO from an expert.
Key Points
- Regex can handle thousands of redirects with a single rule
- Essential for filtering data in Search Console and GA4
- Mastering capture groups simplifies large-scale migrations
Practical Examples
Dynamic redirects
A site uses a regex in .htaccess to redirect all old category URLs: RewriteRule ^category/(.*)$ /cat/$1 [R=301,L]. Thousands of redirects are handled by a single rule.
Search Console filter
An SEO uses the regex ^/blog/(?!2026) in Search Console to filter all blog pages except those from 2026, analyzing older content performance.
Frequently Asked Questions
Regex101.com is the best online tool for testing and understanding regex. For SEO specifically, the Search Console and Screaming Frog documentation provide practical examples. SEO regex typically use a simple subset of the full syntax.
No, Search Console uses RE2 (Google syntax), which is a subset of regex. Lookahead and lookbehind are not supported. Basic features (., *, +, ?, ^, $, |, [], ()) work normally.
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Last updated: 2026-02-07