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Free Regex Tester — Test Regular Expressions Online
Test regular expressions in real-time with match highlighting.
About Regex Tester
Write a regular expression, provide test text, and see matches highlighted in real time with capture groups color-coded individually. Supports all JavaScript regex flags (g, i, m, s, u, y) and shows match positions, groups, and a detailed breakdown of each match. An indispensable tool for developers writing form validation, parsing log files, extracting data from text, or doing search-and-replace operations.
How to Use Regex Tester
- 1Type your regex pattern in the pattern field
- 2Enter test text in the input area below
- 3Matches highlight in real time — capture groups shown separately
- 4Reference the cheat sheet sidebar for quick syntax help
When to Use Regex Tester
- ▸Testing regular expressions before using them in code
- ▸Validating email, phone, and URL formats
- ▸Extracting data patterns from logs and text files
- ▸Learning regex by experimenting with live examples
Frequently Asked Questions
- Which regex flavor does it support?
- It uses JavaScript (ECMAScript) regex syntax, covering lookaheads, capturing groups, character classes, and quantifiers.
- Why doesn't my regex match?
- Different engines have subtle differences. JavaScript doesn't support lookbehinds in all browsers or possessive quantifiers. Check the cheat sheet for supported syntax.