Regex Tester
Regex tester that runs regular expressions against your text with real-time highlighted matches, named and numbered capture groups and flag toggles. Preview replacements while you build and debug patterns, free in your browser.
Embed
What is Regex Tester?
Regex tester that runs regular expressions against your text with real-time highlighted matches, named and numbered capture groups and flag toggles. Preview replacements while you build and debug patterns, free in your browser.
How to Use
- 1Enter pattern— Enter the regular expression pattern.
- 2Select flags— Select flags (g, i, m, s, u, y).
- 3Enter test string— Enter the test string and match results are displayed in real-time.
- 4Check results— Matched parts are highlighted in yellow and capture groups are shown in a table.
- 5Replacement mode— In replacement mode, you can reference capture groups with $1, $2, etc.
Related Tools
Frequently Asked Questions
Ten presets are provided including email, URL, IPv4, Korean phone number, HEX color, HTML tag, and date patterns.
Yes. Named capture groups in the format (?<name>pattern) are supported and displayed in the results table.
Pattern validity is checked in real-time, displaying a red border and error message.
When matching empty strings, lastIndex is automatically incremented, with a maximum limit of 10,000 iterations.
No. All regex processing is performed in the browser.