Question 1

What is a regex tester?

Accepted Answer

A regex tester is a tool that lets you write regular expressions and test them against sample text in real time. QTool.io's Regex Tester highlights matches, shows capture group details, supports all JavaScript regex flags, and includes a replace mode.

Question 2

What regex flags are supported?

Accepted Answer

QTool.io's Regex Tester supports all standard JavaScript regex flags: g (global), i (case insensitive), m (multiline), s (dotall, where . matches newlines), and u (Unicode). You can toggle each flag independently.

Question 3

Can I share my regex pattern with others?

Accepted Answer

Yes, QTool.io's Regex Tester encodes your pattern, flags, and test string into the URL hash. Click the Share button to copy the URL and share it with anyone — they will see your exact regex and test data.

Question 4

Does the regex tester support replace mode?

Accepted Answer

Yes, you can enter a replacement string and see the result in real time. It supports backreferences like $1, $2 for captured groups, making it easy to test search-and-replace patterns before using them in your code.

Token	Description
.	Any character (except newline)
\d	Digit [0-9]
\D	Not a digit
\w	Word character [a-zA-Z0-9_]
\W	Not a word character
\s	Whitespace
\S	Not whitespace
\b	Word boundary
^	Start of string/line
$	End of string/line
*	0 or more
+	1 or more
?	0 or 1 (optional)
{n}	Exactly n times
{n,m}	Between n and m times
[abc]	Character class
[^abc]	Negated class
(abc)	Capturing group
(?:abc)	Non-capturing group
(?=abc)	Positive lookahead
(?!abc)	Negative lookahead
(?<=abc)	Positive lookbehind
a\|b	Alternation (a or b)
\1	Backreference to group 1
(?<name>)	Named capture group

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