How do you use a regex tester?

Enter a pattern, optional flags (g, i, m, s, u, y), and a test string. Matches highlight in the text and appear in the match list with indexes and capture groups.

What is a regular expression?

A regex is a search pattern for matching, validating, extracting, or replacing text. Most languages and editors support a similar dialect of metacharacters and quantifiers.

Which flags matter most?

g finds all matches, i ignores case, m makes ^ and $ line-aware, and s lets . match newlines. Combine flags as needed (for example, gi).

Free tools

Regex Tester

A free regular expression tester. Try out the rest of our free dev resources.

Regular expression

//g

Flags

Test string

Match information

3 matches

He was oddly fascinated by the strangely quickly hummingbird.

Match 1: oddly
Index: 7
Match 2: strangely
Index: 31
Match 3: quickly
Index: 41

Regex cheat sheet

\d  Any digit
\w  Any word character
.   Any character except newline
*   Zero or more
+   One or more
?   Zero or one
^   Start of string
$   End of string
(...) Capture group
[abc] Character class

FAQ

How do you use a regex tester?: Enter a pattern, optional flags (g, i, m, s, u, y), and a test string. Matches highlight in the text and appear in the match list with indexes and capture groups.
What is a regular expression?: A regex is a search pattern for matching, validating, extracting, or replacing text. Most languages and editors support a similar dialect of metacharacters and quantifiers.
Which flags matter most?: g finds all matches, i ignores case, m makes ^ and $ line-aware, and s lets . match newlines. Combine flags as needed (for example, gi).