How do I use this regex tester?

Enter a pattern in the /.../ box, choose flags (g/i/m/s), then paste a test string to see real-time matches and highlighting.

What do the flags g, i, m, s mean?

g = global (find all matches), i = ignore case, m = multiline (^/$ match per line), s = dotAll (. matches newlines).

Why does it say the regex is invalid?

It uses JavaScript regular expressions. If your pattern has a syntax error or uses unsupported features, the status will show invalid with an error.

Can I use common patterns like email/URL/IPv4?

Yes. Click a pattern card in “Common Patterns” to load an example regex and flags, then modify it to fit your needs.

Is it private and offline-friendly?

Yes. Matching runs locally in your browser and nothing is uploaded. After the first load, it can often work offline depending on your cache.

Regex Tester - Free Online Regular Expression Testing Tool

Regular Expression

g i m s

Status: Valid

Matches: 0

Test String

Match Results

Common Patterns

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Matches email addresses

Phone

(\+\d{1,3}[-.\s]?)?$?\d{3}$?[-.\s]?\d{3}[-.\s]?\d{4}

Matches phone numbers

URL

https?://...

Matches HTTP/HTTPS URLs

IPv4

^(?:(?:25[0-5]|...)\.){3}....$

Matches IPv4 addresses

Date

\d{4}-\d{2}-\d{2}|...

Matches common date formats

Credit Card

\d{4}[-\s]?\d{4}[-\s]?\d{4}[-\s]?\d{4}

Matches credit card numbers

Hex Color

#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})

Matches hex color codes

HTML Tag

<\/?[a-z][\s\S]*>

Matches HTML tags

Quick Reference

Characters

. Any character

\d Digit (0-9)

\w Word character

\s Whitespace

Quantifiers

* Zero or more

+ One or more

? Zero or one

{n,m} Between n and m

Anchors

^ Start of string

$ End of string

\b Word boundary

Groups

() Capturing group

(?:) Non-capturing

[abc] Character set

[^abc] Negated set

How to Use

Enter your regular expression in the regex input field
Select appropriate flags (g, i, m, s) as needed
Enter test string to match against your regex
View highlighted matches and detailed results below
Use common patterns for quick testing or reference guide for syntax help