What regex flavor does this tool use?

The tool uses JavaScript (ECMAScript) regular expression syntax, which is compatible with most modern languages including Python (with minor differences) and Ruby.

How do I make a regex case-insensitive?

Add the "i" flag to your pattern. In the tool, check the "Case Insensitive" checkbox, or write your pattern as /pattern/i.

What does the "global" flag do?

Without the global (g) flag, only the first match is returned. With the g flag, all matches in the test string are found and highlighted.

How do I test a regex for email validation?

A basic email regex is: /^[^@\s]+@[^@\s]+\.[^@\s]+$/. Paste it into the pattern field and enter test email addresses to verify it matches correctly.

Developer Tools

Test regular expressions with live highlighting and match details

Regex Tester

Test regular expressions with live highlighting and match details

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Regular Expression Testing

Regex Pattern

Flags

Global (g)Case Insensitive (i)Multiline (m)Dotall (s)

Test Text

Learn more about Regex Tester

About Regex Tester

Test regular expressions against sample text with live match highlighting. See all matches, capture groups, and match positions instantly. Supports JavaScript regex syntax with all common flags (g, i, m, s).

Key features

Live match highlighting as you type the pattern
Shows all match positions and captured groups
Supports flags: global, case-insensitive, multiline
Displays match count and match details panel
Quick reference for common regex patterns

How to use Regex Tester

1Enter your regular expression pattern in the pattern field
2Set any flags (g for all matches, i for case-insensitive)
3Paste or type the test string below
4Matches are highlighted in real-time; capture groups shown in the details panel

Frequently asked questions

What regex flavor does this tool use?: The tool uses JavaScript (ECMAScript) regular expression syntax, which is compatible with most modern languages including Python (with minor differences) and Ruby.
How do I make a regex case-insensitive?: Add the "i" flag to your pattern. In the tool, check the "Case Insensitive" checkbox, or write your pattern as /pattern/i.
What does the "global" flag do?: Without the global (g) flag, only the first match is returned. With the g flag, all matches in the test string are found and highlighted.
How do I test a regex for email validation?: A basic email regex is: /^[^@\s]+@[^@\s]+\.[^@\s]+$/. Paste it into the pattern field and enter test email addresses to verify it matches correctly.