What is a regular expression (regex)?

A regular expression is a sequence of characters that defines a search pattern. It's used to find, match, and manipulate strings in programming and text processing.

What flags are available?

g (global — find all matches), i (case insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — . matches newlines too).

What regex syntax does this tool use?

JavaScript (ECMAScript) regex syntax, which is supported by all modern browsers.

How do I match a literal special character?

Escape it with a backslash. For example, to match a literal dot, use \. instead of . (which matches any character).

What are capture groups?

Groups enclosed in parentheses ( ) capture the matched text as a separate result. Named groups use (? ...) syntax.

Regex Tester

Developer

Test and debug regular expressions live with match highlights.

Pattern

//g

Common Patterns

Test String

How to use Regex Tester

1Enter your regular expression pattern in the Pattern field (without slashes).
2Select any flags you need — global (g), case insensitive (i), multiline (m).
3Type or paste your test string in the Test String area.
4Matches are highlighted in real time. View all matches and capture groups below.

Frequently Asked Questions

Learn More

Regular Expression — Wikipedia

History, syntax, and uses of regular expressions

Regex Guide — MDN

Complete JavaScript regex syntax reference

POSIX Regular Expressions

Different regex standards and their differences

JSON Formatter

Format, validate, and minify JSON with syntax highlighting.

Developer

Base64 Encoder / Decoder

Encode and decode Base64 strings instantly online.

Developer

URL Encoder / Decoder

Encode and decode URL strings and query parameters.

Developer

Regex Tester

How to use Regex Tester

Frequently Asked Questions

Learn More

You might also like