Regex Tester

Test regular expressions with real-time matching and highlighting. Uses JavaScript regex engine.

Regular Expression

/ /

Test String

Match Results

Common Regex Patterns

Pattern	Description	Example Match
`[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z]{2,}`	Email address	user@example.com
`https?://[^\s]+`	URL	https://example.com
`\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b`	IPv4 address	192.168.1.1
`^\d{4}-\d{2}-\d{2}$`	Date (YYYY-MM-DD)	2026-01-15
`^#?([a-fA-F0-9]{6}\|[a-fA-F0-9]{3})$`	Hex color	#ff5733

Regex Quick Reference

Token	Description
`.`	Any character except newline
`\d`	Digit [0-9]
`\w`	Word character [a-zA-Z0-9_]
`\s`	Whitespace
`*`	0 or more
`+`	1 or more
`?`	0 or 1
`{n,m}`	Between n and m times
`^`	Start of string/line
`$`	End of string/line
`(abc)`	Capture group
`[abc]`	Character class
`a\|b`	Alternation (a or b)

Frequently Asked Questions

What is a regular expression (regex)?▼

A regular expression is a sequence of characters that defines a search pattern. Regex is used for string matching, validation, search-and-replace, and data extraction in virtually every programming language.

What do regex flags like g, i, and m mean?▼

The 'g' flag enables global matching (find all matches, not just the first). The 'i' flag makes matching case-insensitive. The 'm' flag enables multiline mode where ^ and $ match line starts/ends.

How do I match an email address with regex?▼

A common email regex pattern is: ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ — though perfect email validation with regex is extremely complex. For production use, consider using your language's built-in email validation.