Tools / Development

Regex Tester

Enter a regular expression and test text to highlight matches and inspect capture groups.

This page participates in the Coupang Partners program and may earn a commission from qualifying purchases.

Regex Tester

Pattern

//g

Flags

Test text

2 matches

Contact: kuro@example.com or admin@site.co.kr

Groups

Index 9Full match: kuro@example.com

Index 29Full match: admin@site.co

This page participates in the Coupang Partners program and may earn a commission from qualifying purchases.

Need to compare two pieces of text? Try the Text Compare tool.

첫 번째 댓글을 남겨보세요!

This page participates in the Coupang Partners program and may earn a commission from qualifying purchases.

Tool info

Category Development

Processing Directly in your browser

Data storage Not stored

Updated 2026-08-21

How to use

Type a regular expression into the pattern box.

Toggle the g, i, m, s, and u flags as needed.

Enter test text and matches are highlighted instantly.

If the pattern has capture groups, each match's group values appear below the result.

FAQ

자주 묻는 질문

Q1. Is my test text sent to a server?

No. Matching runs entirely in your browser's JavaScript engine — neither the pattern nor the test text is ever sent to a server.

Q2. What does the g flag do?

With the g (global) flag on, the tool finds every match in the text instead of stopping at the first one. With it off, only the first match found is shown.

Q3. What are capture groups?

Parts of a pattern wrapped in parentheses () are called capture groups. For example, (\d{3})-(\d{4}) splits a phone number into two parts, extracted separately as group 1 and group 2.

Q4. What regex flavor does this tool use?

It uses the browser's built-in JavaScript (ECMAScript) regex engine. The syntax is mostly similar to PCRE or Python's re module, but some features — like lookbehind support — can differ.

Q5. What happens if my regex is invalid?

An error message appears below the pattern box, and no match results are calculated until the pattern is fixed.

Favorites

This page participates in the Coupang Partners program and may earn a commission from qualifying purchases.