How do I test a regular expression online?

Enter your regex pattern and test string. Matches are highlighted in real time and capture groups are displayed below. You can toggle flags like global (g), case-insensitive (i), and multiline (m).

What regex flags are available?

The tool supports global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u) flags. Toggle them to change matching behavior.

Regex Tester

Pattern

Common Patterns

Test String

Replace

Replacement String

About the Regex Tester

Test regular expressions with real-time matching, capture groups, and flags. Free online regex debugger.

The Regex Testerruns entirely in your browser — your data is never uploaded to a server, so it stays private and works instantly, even offline. It's completely free, requires no sign-up, and works on desktop and mobile.

Frequently Asked Questions

How do I test a regular expression online?: Enter your regex pattern and test string. Matches are highlighted in real time and capture groups are displayed below. You can toggle flags like global (g), case-insensitive (i), and multiline (m).
What regex flags are available?: The tool supports global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u) flags. Toggle them to change matching behavior.

Related tools

CSS Unit Converter
Color Converter
SEO Checklist