Regex Tester

Regex Tester lets you write, test, and debug regular expressions in real time, with match highlighting, capture group breakdowns, and flag toggling.

When to use this tool

• Debugging a regex that isn't matching expected text
• Learning how regex patterns work with live feedback
• Validating input patterns (email, phone, ZIP codes)
• Building search-and-replace patterns

How it works

Compiles the regex using the browser's built-in RegExp engine and runs it against your test string on every keystroke. Matches are highlighted in the input, and capture groups are displayed separately with their positions.