What is the difference between $1 and \1 in replacement?

$1 is the JavaScript replacement syntax; \1 is the sed/Perl syntax. Use $1 in JS-based tools. Named capture groups can be referenced as $ in modern JS.

My regex is too greedy — how do I limit matches?

Use non-greedy quantifiers (*?, +?) to match the shortest possible string, or replace .* with more specific character classes. Always test on edge cases — greedy regex is the most common source of unexpected replacements.

TASK

Find and replace text using a regular expression

Search for patterns (not just literal strings) in text and replace matches with a template that can reference capture groups.

1

Regex find-and-replace goes beyond literal substitution: it matches patterns (all email addresses, all numbers, repeated whitespace) and can use captured submatches in the replacement (e.g. swap first and last name).
2

Regex Replace →
Enter the regex pattern, flags (g for global, i for case-insensitive), and replacement template (use $1, $2 for capture groups). The tool shows all matches and the replaced output.
3

Regex Tester →
Test the pattern first in the regex tester to confirm it matches what you expect before applying the replacement — this avoids catastrophic replacements on unexpected input.

Frequently asked questions

What is the difference between $1 and \1 in replacement?: $1 is the JavaScript replacement syntax; \1 is the sed/Perl syntax. Use $1 in JS-based tools. Named capture groups can be referenced as $<name> in modern JS.
My regex is too greedy — how do I limit matches?: Use non-greedy quantifiers (*?, +?) to match the shortest possible string, or replace .* with more specific character classes. Always test on edge cases — greedy regex is the most common source of unexpected replacements.