⚡ Developer Tools

Free Regex Tester & Debugger

Test regular expressions in real time with instant match highlighting, capture groups, and flag toggles. Supports JavaScript regex syntax — 100% client-side.

Pattern

/ /

Replace

Matches will be highlighted here in real time...

❌

📧

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

🔗

URL

https?:\/\/[^\s/$.?#].[^\s]*

📱

Phone (US)

$?[0-9]{3}$?[-.\s]?[0-9]{3}[-.\s]?[0-9]{4}

🏷️

HTML Tag

<([a-z]+)([^<]*)(?:>(.*?)<\/\1>)

How to Use This Regex Tester

Enter Pattern

Type your regex pattern and toggle flags (global, case-insensitive, multiline, etc.).

Add Test String

Paste the text you want to test against. Matches highlight instantly as you type.

Review & Export

Switch to Match List to see all matches with groups. Copy regex or matches.

What This Tool Does

Real-time matching — matches are highlighted instantly as you type the pattern or test string. No "Run" button needed. Capture groups are shown separately in the Match List tab with $1, $2, etc. labels.

Flag toggles — click g (global), i (case-insensitive), m (multiline), s (dotAll), or u (unicode) to change regex behaviour. Replace mode — enter a replacement string and click Replace to see the result with group references ($1, $2).

Uses JavaScript's native RegExp engine, so patterns behave exactly as they would in your JS code.

Is This Tool Free and Private?

Yes. Runs 100% in your browser. No regex patterns or test strings are sent anywhere.

Frequently Asked Questions

JavaScript's native RegExp engine. Patterns work identically to new RegExp() in your browser's JS runtime. Lookbehinds, named groups, and Unicode properties are supported in modern browsers.

g = find all matches (not just the first). i = case-insensitive. m = ^ and $ match line starts/ends. s = dot matches newlines. u = full Unicode support.

No. Everything runs in your browser. No data is ever transmitted.