Regex Generator
Common regex patterns ready to use. 20 presets for email, phone, URL, and more.
Common Patterns
🔍 What Is a Regex Generator?
A regular expression (regex) is a sequence of characters that defines a search pattern, widely used for string matching and data validation. Writing regex from scratch can be tricky because the syntax is not always intuitive, especially for complex patterns. This regex generator provides over 20 ready-to-use preset patterns for common use cases like email validation, phone numbers, URLs, IP addresses, and more. Simply pick a preset, tweak it if needed, and test it against your own input in real time — no guesswork required.
📋 Common Regex Patterns
Email Validation
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ — Matches standard email formats with alphanumeric characters, dots, hyphens, and common special characters before the @ symbol. One of the most frequently used patterns in web development for form validation and data cleaning.
Phone Number Validation
Supports US phone number formats including optional country code, parentheses around area code, and various separators (dashes, dots, spaces). Patterns like (555) 123-4567 or 555-123-4567 are all matched.
URL and IP Address
Validates HTTP/HTTPS URLs with subdomains, paths, and query strings. Also includes patterns for IPv4 addresses (0.0.0.0 to 255.255.255.255) and IPv6 addresses. Useful for web scraping, log analysis, and network configuration validation.
Password Strength
Validates passwords that contain at least one letter, one digit, and one special character, with a minimum length of 8 characters. Uses lookahead assertions (?=...) — a classic example of advanced regex techniques in practice.
📖 Basic Regex Syntax
| Syntax | Description | Example |
|---|---|---|
| . | Any single character | a.c → abc, a1c |
| * | Zero or more repetitions | ab*c → ac, abc, abbc |
| + | One or more repetitions | ab+c → abc, abbc |
| ? | Zero or one occurrence | colou?r → color, colour |
| \d | Any digit (0-9) | \d+ → 123, 456 |
| \w | Word character (letter, digit, underscore) | \w+ → hello_123 |
| [abc] | Character class (a or b or c) | [aeiou] → vowels |
| ^, $ | Start and end of string | ^abc$ → exactly abc |
⚙️ Regex Flags Explained
- g (global) — Finds all matches in the input string instead of stopping after the first match.
- i (case insensitive) — Matches letters regardless of case. For example, ABC and abc are treated identically.
- m (multiline) — Makes ^ and $ match the start and end of each line, rather than the entire string.
Frequently Asked Questions
What is a regular expression?▼
A regular expression (regex) is a pattern-matching syntax used to search, match, and manipulate strings. It is supported by virtually all programming languages and is widely used for data validation, text parsing, and search-and-replace operations.
Can I modify the preset patterns?▼
Yes. After selecting a preset pattern, you can freely edit it in the pattern input field. Any changes are immediately reflected in the test results below.
How do I test my regex?▼
Select or type a regex pattern, then enter the strings you want to validate in the test area (one per line). Matching lines appear in green with a checkmark, and non-matching lines appear in red with an X mark.