Regex Generator
Stop fighting regex syntax. Describe what you want to match — “UK postcodes”, “prices like $1,299.99”, “lines that start with ERROR” — optionally paste sample text, and get a pattern with a plain-English explanation. Every example is re-tested with a real regex engine, and you can refine it in the built-in tester.
Type a description, choose the regex flavour and optionally paste sample text. AI (Google Gemini) writes the pattern, flags and an explanation, plus examples that should and shouldn't match; your browser then runs each example through the real engine and marks any that fail. Or pick a proven pattern from the library.
Or start from a proven pattern
- Email address
/[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}/g - URL (http/https)
/https?:\/\/[^\s/$.?#].[^\s]*/gi - IPv4 address
/\b(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\b/g - Date (YYYY-MM-DD)
/\b\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])\b/g - Time (HH:MM, 24h)
/\b(?:[01]\d|2[0-3]):[0-5]\d\b/g - Hex colour
/#(?:[0-9a-fA-F]{3}){1,2}\b/g - UUID
/\b[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}\b/gi - Phone (international E.164)
/\+[1-9]\d{7,14}\b/g - US ZIP code
/\b\d{5}(?:-\d{4})?\b/g - UK postcode
/\b[A-Z]{1,2}\d[A-Z\d]? ?\d[A-Z]{2}\b/gi - Strong password (8+, upper, lower, digit, symbol)
/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^A-Za-z\d]).{8,}$/ - Slug
/^[a-z0-9]+(?:-[a-z0-9]+)*$/ - Whitespace at line ends
/[ \t]+$/gm - HTML tag
/<\/?([a-z][a-z0-9-]*)\b[^>]*>/gi - Number (int or decimal)
/-?\b\d+(?:\.\d+)?\b/g - Credit card-like number (16 digits)
/\b(?:\d{4}[ -]?){3}\d{4}\b/g
Instant Results
Live checks in seconds
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Suggest a Feature or Improvement for Regex Generator
Need custom options, higher limits, or extra format support? Let our engineering team know!
How to use Regex Generator
- 1Describe what you want to match.
- 2Choose the regex flavour and add sample text if you have it.
- 3Generate, then check the live test results.
- 4Fine-tune the pattern in the tester below.
Trust, but test
AI is good at drafting regular expressions but can get edge cases wrong, so this tool never asks you to take the pattern on faith: each example is executed in your browser and failures are shown in red. Always test with real data, especially for validation that matters (emails, IDs, security filters).
For validating complex formats like emails or URLs, a simple regex plus a real check (sending a confirmation email, parsing with URL()) beats one giant pattern.
Proven patterns
The library includes tested patterns for emails, URLs, IPv4 addresses, dates, times, hex colours, UUIDs, phone numbers, postcodes, slugs and more. Experiment freely in the Regex Tester.
Frequently Asked Questions
Is my text sent anywhere?
Your description and optional sample text are sent to Google's Gemini API to generate the pattern and aren't stored by us. Testing happens in your browser. Don't paste confidential data as samples.
Is there a limit?
It's free with a daily allowance per visitor to keep AI costs sustainable.
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