Regex Tester
Test regular expressions in real-time
Expression
//gm
Flags:
Test String
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Match Highlights
Matches will be highlighted here...
Match Information
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What is Regex Tester?
Regular expressions (regex) are powerful pattern-matching sequences used in text processing, input validation, search-and-replace, and data extraction. Regex syntax can be difficult to debug without visual feedback. DailyDevTools' Regex Tester highlights all matches in real-time as you type, shows capture groups, supports all JavaScript regex flags (g, i, m, s, u), and explains what each part of your pattern does in plain English.
How to use Regex Tester
- 1Enter your regex pattern in the Pattern field (without wrapping slashes)
- 2Select the flags you need: g for global, i for case-insensitive, m for multiline
- 3Paste your test string in the Test area — all matches are highlighted instantly
- 4Review the Matches panel to see each match, its index, and any named capture groups
Frequently asked questions
Which regex flavour does this use?
The tester uses JavaScript's built-in RegExp engine following the ECMAScript specification. Most patterns are portable across languages, but some features like lookbehind may differ.
How do I match a literal dot or special character?
Escape special regex characters with a backslash. For a literal dot use \., for a dollar sign use \$. The tester shows real-time errors for invalid patterns.
Can I test named capture groups?
Yes. Use the (?<name>...) syntax. Named groups appear in the Matches panel labeled by their group name, making complex patterns much easier to understand and debug.