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Regex Tester & Debugger

Test, analyze, and build your regular expressions dynamically in real-time. Safe, client-side, instant matching.

Regular Expression

/ /
g - Global
i - Case Insensitive
m - Multiline
s - Singleline (dotAll)
u - Unicode
Match Details
Type regex and test string to inspect matches.

Test String

0 matches
0 ms

Regex Quick Reference

[abc]Any single character in set
[^abc]Any character not in set
[a-z]Character range
.Any character except newline
\dAny digit (0-9)
\wAlphanumeric character
\sWhitespace character
a* | a+ | a?0+ | 1+ | 0 or 1 quantifiers
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What is an Online Regex Tester?

A Regular Expression (Regex) is a sequence of characters that forms a search pattern. They are incredibly powerful tools for text matching, replacement, parsing, and data validation. Our free online Regex Tester helps you write, test, debug, and optimize patterns in real-time, giving you instant visual feedback on match locations, capture groups, and processing speed.

How to Use

  1. Enter your regex pattern inside the slash symbols (e.g. \d+ to match numbers)
  2. Select flags using the interactive pills or type them in directly (e.g. g for global, i for case-insensitive)
  3. Type or paste your test content into the Test String panel
  4. Review matches highlighted dynamically, and check the Match Details panel to see captured groups

Frequently Asked Questions

No, not at all! This Regex Tester performs all matching operations inside your browser using client-side JavaScript. None of your regular expressions or test string data is transmitted over the network, ensuring absolute privacy.

This tool is based on the native JavaScript Regular Expression engine. It supports modern features including lookarounds (lookahead and lookbehind), unicode flags, and backreferences.

Common flags are: g (global): finds all matches rather than stopping at the first; i (ignore case): makes matches case-insensitive; m (multiline): caret (^) and dollar ($) match start/end of lines; s (dotAll): dot (.) matches newlines.

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