What are the 6 JavaScript regex flags?

JavaScript supports six flags: g (global) finds all matches instead of stopping at the first; i (case insensitive) ignores letter case; m (multiline) makes ^ and $ match the start and end of each line; s (dot all) allows the dot to match newline characters; u (unicode) enables full Unicode mode for correct handling of characters outside the Basic Multilingual Plane; y (sticky) anchors matching to the exact position of the last match.

How do I share a regex with someone?

Click the Share URL button. The tool encodes your current pattern, flags, and test text into the page URL and copies it to your clipboard. Anyone who opens that link will see the tool pre-populated with your exact setup.

Regex Tester — Test Regular Expressions Online Free

Regex Tester

Real-Time Pattern Matching — All 6 JS Flags · Capture Groups · Find & Replace · Share URL

Test and debug regular expressions instantly as you type. Highlights every match, extracts capture groups, shows character positions, and supports all six JavaScript flags. Includes a find-and-replace panel, eight pre-built patterns, a quick-reference cheat sheet, and a shareable URL. Runs 100% in your browser — your data never leaves your device.

🔒 Runs in your browser — no data is ever transmitted to a server

Regular Expression Pattern

Flags

Quick Patterns

Test Text & Match Results

Highlighted Matches

Matches: 0

Unique: 0

Groups: 0

Find & Replace

Find (uses pattern above)

Replace with (use $1, $2 for groups)

Result

📖 Regex Quick Reference Click to expand ▾

Character Classes

.any char (not newline)

\wword char [a-zA-Z0-9_]

\ddigit [0-9]

\swhitespace

\W \D \Snegations of above

[abc]any of a, b, or c

[^abc]not a, b, or c

[a-z]char in range a–z

Anchors

^start of string / line

$end of string / line

\bword boundary

\Bnon-word boundary

Quantifiers

*0 or more (greedy)

+1 or more (greedy)

?0 or 1 (optional)

{n}exactly n times

{n,m}between n and m

*? +? ??lazy (non-greedy)

Groups & Lookaround

(...)capture group

(?:...)non-capturing group

(?<n>...)named capture group

\1 \2backreference to group

(?=...)positive lookahead

(?!...)negative lookahead

(?<=...)positive lookbehind

(?<!...)negative lookbehind

Flags (JS)

gfind all matches

icase insensitive

mmultiline ^ and $

s. matches newlines

ufull unicode mode

ysticky matching

Escape Sequences

\n \t \rnewline, tab, return

\. \+ \*literal special chars

a|balternation (a or b)

All processing happens locally in your browser — your data is never transmitted to a server.

How to Use the Regex Tester

Enter Your Pattern

Type or paste a regular expression into the Pattern field. You do not need to add the leading or trailing slash — those are shown for context only. To get started quickly, click any of the eight pre-built pattern buttons to load a working example for emails, URLs, phone numbers, IP addresses, dates, hex colors, usernames, or passwords.

Choose Your Flags

Toggle any of the six JavaScript flags to change how matching behaves. Global (g) finds every match in the text rather than stopping at the first. Case Insensitive (i) ignores letter case. Multiline (m) makes the caret and dollar anchors apply per line. Dot All (s) lets the dot match newline characters. Unicode (u) enables full Unicode mode. Sticky (y) anchors matching to the last match position.

Paste Your Test Text and Review Results

Type or paste the text you want to test in the Test Text area. Matches are highlighted in real time in the output box below it. The stats bar shows the total match count, the number of unique matched strings, and the number of capture groups found. Each match is listed with its full text, character start and end positions, and any capture group values extracted from it.

Use Find and Replace

The Find and Replace panel automatically syncs your current pattern. Enter a replacement string and the result appears instantly. Use $1, $2, and so on to reference captured groups in your replacement — for example, replacing (\w+)\s(\w+) with $2, $1 will swap first and last name order across all matches.

Frequently Asked Questions

What regex engine does this tester use?

What are the six JavaScript regex flags?

How do capture groups work in this tool?

How do I share my regex with a colleague?

Is my data sent to a server?

What do the match position numbers mean?

Regex Tester

How to Use the Regex Tester

Frequently Asked Questions

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