How do I test a regular expression online?

Paste your regex pattern into the Regex Tester, enter your test string below, and matches will be highlighted in real time with group details shown.

What does the g flag do in regex?

The g (global) flag makes the regex find all matches in the string, not just the first one.

How do I match a whole word in regex?

Use word boundary anchors: \bword\b matches the exact word without partial matches inside other words.

What is a capture group in regex?

Capture groups are created with parentheses (like (\d+)) and allow you to extract specific parts of the match.

How do I make a regex case-insensitive?

Add the i flag after the pattern. In JavaScript: /pattern/i, or enable the case-insensitive option in the regex tester.

Regex Tester – Dev Tools Online — Free Developer Utilities

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Quick Answer

A regular expression (regex) is a pattern used to match, search, and extract text — for example, \d+ matches any sequence of digits in a string. This tester lets you write and test regex patterns in real time with live match highlighting.

Test regular expressions live with match highlighting and a library of common patterns.

Regular Expression

/ /

Test String

Matches: 0

Status: —

Highlighted Output

Common Patterns

Cite This Tool

Regex Tester. (2026). DevTools Online. Retrieved from https://devutilitypro.com/regex-tester/

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