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Regex Pattern Generator - Free Online Tool

Last updated March 22, 2026

Regex Pattern Generator Examples

The Regex Pattern Generator creates regular expression patterns for common validation and matching tasks. Below are examples of generated patterns with explanations.

Email Validation Pattern

Generate a practical email validation regex:

Generated pattern (JavaScript):
  /^[\w.\-+]+@[\w\-]+\.[a-zA-Z]{2,}$/

Explanation:
  ^           — start of string
  [\w.\-+]+   — one or more word chars, dots, hyphens, or plus signs (local part)
  @           — literal @ symbol
  [\w\-]+     — one or more word chars or hyphens (domain name)
  \.          — literal dot
  [a-zA-Z]{2,}— two or more letters (TLD)
  $           — end of string

Matches:
  user@example.com        ✓
  first.last@domain.org   ✓
  user+tag@sub.domain.co  ✓

Rejects:
  @example.com            ✗ (no local part)
  user@                   ✗ (no domain)
  user@domain             ✗ (no TLD)

URL Validation Pattern

Generate a URL matching pattern:

Generated pattern:
  /^https?:\/\/[\w\-]+(\.[\w\-]+)+(\/[\w\-._~:/?#[\]@!$&'()*+,;=%]*)?$/

Matches:
  https://example.com              ✓
  http://sub.domain.org/path       ✓
  https://example.com/path?q=1#s  ✓

Rejects:
  ftp://example.com                ✗
  example.com                      ✗ (no protocol)

US Phone Number Pattern

Generate a flexible US phone number pattern:

Generated pattern:
  /^\+?1?[\s.\-]?\(?\d{3}\)?[\s.\-]?\d{3}[\s.\-]?\d{4}$/

Matches all common US formats:
  (415) 823-7491    ✓
  415-823-7491      ✓
  415.823.7491      ✓
  4158237491        ✓
  +1 415 823 7491   ✓
  1-415-823-7491    ✓

Date Patterns

Generate date validation patterns for different formats:

ISO date (YYYY-MM-DD):
  /^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/

US date (MM/DD/YYYY):
  /^(0[1-9]|1[0-2])\/(0[1-9]|[12]\d|3[01])\/\d{4}$/

European date (DD.MM.YYYY):
  /^(0[1-9]|[12]\d|3[01])\.(0[1-9]|1[0-2])\.\d{4}$/

Time (HH:MM or HH:MM:SS):
  /^([01]\d|2[0-3]):[0-5]\d(:[0-5]\d)?$/

IP Address Patterns

Generate IPv4 and IPv6 validation patterns:

IPv4:
  /^(\d{1,3}\.){3}\d{1,3}$/

IPv4 with range validation (0-255):
  /^((25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(25[0-5]|2[0-4]\d|[01]?\d\d?)$/

IPv6 (simplified):
  /^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$/

Password Strength Pattern

Generate a strong password validation pattern using lookaheads:

Generated pattern (8+ chars, upper, lower, digit, special):
  /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/

Explanation:
  (?=.*[a-z])       — must contain at least one lowercase letter
  (?=.*[A-Z])       — must contain at least one uppercase letter
  (?=.*\d)          — must contain at least one digit
  (?=.*[@$!%*?&])   — must contain at least one special character
  [A-Za-z\d@$!%*?&]{8,} — 8 or more allowed characters

Matches:
  Secure@123    ✓
  P@ssw0rd!     ✓

Rejects:
  password      ✗ (no uppercase, digit, or special)
  Password1     ✗ (no special character)

Credit Card Number Pattern

Generate a credit card validation pattern:

Visa (starts with 4, 16 digits):
  /^4\d{15}$/

Mastercard (starts with 51-55 or 2221-2720):
  /^(5[1-5]\d{14}|2(2[2-9]\d|[3-6]\d{2}|7[01]\d|720)\d{12})$/

American Express (starts with 34 or 37, 15 digits):
  /^3[47]\d{13}$/

Any major card (with optional spaces/hyphens):
  /^[\d\s\-]{13,19}$/

Hex Color Pattern

Generate a hex color code validation pattern:

Generated pattern:
  /^#([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$/

Matches:
  #fff        ✓ (3-digit shorthand)
  #ffffff     ✓ (6-digit full)
  #1A2B3C     ✓ (mixed case)

Rejects:
  #gg0000     ✗ (invalid hex chars)
  ffffff      ✗ (missing #)
  #12345      ✗ (wrong length)

Postal Code Patterns

Generate postal code patterns for different countries:

US ZIP code:
  /^\d{5}(-\d{4})?$/
  Matches: 90210, 90210-1234

UK postcode:
  /^[A-Z]{1,2}\d[A-Z\d]?\s?\d[A-Z]{2}$/i
  Matches: SW1A 1AA, EC1A 1BB

Canadian postal code:
  /^[A-Z]\d[A-Z]\s?\d[A-Z]\d$/i
  Matches: K1A 0A9, M5V3L9

German PLZ:
  /^\d{5}$/
  Matches: 10115

Named Capture Groups for Data Extraction

Generate a log line parser with named groups:

Generated pattern:
  /(?<timestamp>\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}) (?<level>INFO|WARN|ERROR) (?<message>.+)/

Input: "2026-03-17 14:23:01 ERROR Database connection failed"

Extracted:
  timestamp: "2026-03-17 14:23:01"
  level:     "ERROR"
  message:   "Database connection failed"

JavaScript usage:
  const match = line.match(pattern);
  const { timestamp, level, message } = match.groups;

Pattern in Multiple Languages

The same email pattern generated for different languages:

JavaScript:
  /^[\w.\-+]+@[\w\-]+\.[a-zA-Z]{2,}$/

Python:
  import re
  pattern = re.compile(r'^[\w.\-+]+@[\w\-]+\.[a-zA-Z]{2,}$')

Java:
  Pattern pattern = Pattern.compile("^[\\w.\\-+]+@[\\w\\-]+\\.[a-zA-Z]{2,}$");

PHP (PCRE):
  preg_match('/^[\w.\-+]+@[\w\-]+\.[a-zA-Z]{2,}$/', $email)

Pre-built templates for email, URL, phone, date, IP, and more
Describe custom formats and get the matching regex
Test patterns against sample strings with real-time highlighting
Named capture groups for structured data extraction
Lookahead-based password strength validation
Generate patterns for JavaScript, Python, Java, and PCRE
Plain-English explanation of what each pattern matches
Patterns designed to avoid catastrophic backtracking

Regex Pattern Generator Free Online Tool 2026

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