Regex Tester & Cheat Sheet

Test regular expressions dynamically in your browser. Enter your regex pattern and flags, input sample text, and review captured patterns instantly.

Regex Pattern:

/ /

Regex Flags:

global (g) ignoreCase (i) multiline (m)

Test String:

Matched Outputs Summary

Matches Found:

Visual Matches Preview

Matches highlighted in yellow...

Capture Groups Breakdown

Match	Index	Full Match & Groups Details
No capture group results compiled.

Regular Expressions Syntax Cheat Sheet

Character	Name	Matches Description
`.`	Any Character	Matches any single character except newline.
`\d`, `\D`	Digit, Non-Digit	`\d` matches [0-9]. `\D` matches any character other than digits.
`\w`, `\W`	Alphanumeric, Non-Word	`\w` matches basic word characters [a-zA-Z0-9_]. `\W` matches symbols/spaces.
`*`, `+`, `?`	Quantifiers	`*` (0 or more times), `+` (1 or more times), `?` (0 or 1 time).
`{n}`, `{n,m}`	Range Quantifiers	Matches exactly `n` times, or between `n` and `m` times.
`[a-z]`, `[^a-z]`	Character Set / Negation	Matches any character inside the brackets. `^` negates the set.
`^`, `$`	Anchors	`^` asserts position at the start of string. `$` asserts position at the end.
`(...)`	Capture Group	Groups multiple tokens together and saves matched strings for reference.

What are Regular Expressions and How are they Used?

A Regular Expression (Regex) is a sequence of characters defining a search pattern. They are widely used in search engines, validation scripts, database query modules, and text editors for pattern-matching operations.

Writing regular expressions can be error-prone. This interactive tester parses JavaScript regex rules and formats matches dynamically as you type. By running locally in your browser, it provides a safe sandbox to test patterns against sensitive inputs without data leaks.

Frequently Asked Questions (FAQ)

Q: Why am I getting a regex syntax error?

A: Ensure that parentheses (), square brackets [], and curly braces {} are properly closed. Escape special syntax characters like /, ., or ? with a backslash \ if you want to match them literally.

Q: What is the difference between global (g) and multiline (m) flags?

A: The g flag queries all match occurrences in the string instead of stopping after the first match. The m flag changes anchors ^ and $ to match the start/end of each individual line instead of the entire string.

Q: Are backreferences and advanced groups supported?

A: This tool runs on standard browser JavaScript RegExp engines, supporting capture groups, lookaheads, lookbehinds, and basic backreferences.