Regex Tester / Find & Replace

A regular expression (regex) is a compact language for describing patterns in text — for searching, validating a format, or replacing matches. This tool highlights matches in real text as you type the pattern, breaks out capture groups, and supports a find-and-replace mode.

How to use it

• Search: enter a pattern and some test text — every match is highlighted and capture groups are broken out separately.
• Replace: switch to Replace mode, provide a replacement template (referencing groups with $1, $2), and see the result instantly.
• Flags (g, i, m, s) toggle independently and immediately affect how many matches are found and how.

Common uses

• Building and debugging a regex before pasting it into code — you see the result without running the program.
• Bulk find-and-replace against a pattern (e.g. reformatting phone numbers or dates).
• Validating an input format (email, card number, slug) against real examples.

Things to keep in mind

Greedy quantifiers (*, +) grab as many characters as possible — add ? for the minimal match instead (e.g. .*? instead of .*).

Syntax varies slightly between languages — an expression that works here (a JavaScript engine) may need adjusting for PCRE, .NET, or Python.