Regex Replace

Find and replace using regular expressions — with capture group references, live preview, and match count.

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Quick examples:

About Regex Replace

Regular expression replacement is one of the most powerful text transformation techniques available. Unlike simple find-and-replace, regex replacement can match complex patterns, capture parts of the matched text with capturing groups, and use those captured parts in the replacement string using backreferences ($1, $2, etc.).

For example, to reformat dates from YYYY-MM-DD to DD/MM/YYYY, use the pattern (\d{4})-(\d{2})-(\d{2}) with replacement $3/$2/$1. The three groups capture year, month, and day respectively, and the replacement reorders them. This kind of structural transformation is impossible with simple string replacement.

Named capture groups ((?<year>\d{4})) allow you to use descriptive names like $<year> instead of numeric indices in replacements, making complex patterns more readable and maintainable. The live preview updates as you type so you can see the effect of your pattern and replacement immediately.

Frequently Asked Questions

How do I reference capture groups in the replacement?
Use $1, $2, $3, etc. to reference the 1st, 2nd, 3rd capturing group. For named groups (?<name>...), use $<name>. Use $& to insert the entire matched string. Use $` (backtick) for text before the match and $' (single quote) for text after the match.
How do I replace only the first occurrence?
Remove the 'g' (global) flag from the flags field. Without the global flag, JavaScript's replace() only replaces the first match found in the string.
How do I delete all matches (replace with nothing)?
Leave the replacement field empty. An empty replacement string effectively removes all matched text from the output. For example, use the pattern <[^>]+> with empty replacement and the 'gi' flags to strip all HTML tags from text.

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