Regex Generator
Reference tested regular expression patterns for emails, URLs, IP addresses, and numbers.
Regex Match Tester & Validator
Test JavaScript regular expression patterns against test strings with live match count.
About Regex Generator
The Interactive Regular Expression Generator creates customized Regular Expression (Regex) patterns for common validation scenarios (Emails, URLs, IP Addresses, Passwords, Phone Numbers, Credit Cards, Dates) with flag options and real-time test matching.
How to Use Regex Generator
Step 1
Select a regex preset from the library or choose custom pattern builder.
Step 2
Adjust matching criteria (length limits, character rules, flags).
Step 3
Test your pattern with sample strings in the live validator.
Step 4
Click "Copy Regex".
Practical Use Cases for Regex Generator
Form Validation & Input Sanitization
Generate robust regex patterns for frontend React form validators and backend API input validation libraries (Zod, Joi, Yup).
Log Parsing & Data Extraction
Build regex capture groups to extract timestamps, IP addresses, and error codes from server log files.
Input & Output Examples
Generating Strong Password Regex
Requirements: Min 8 chars, 1 uppercase, 1 lowercase, 1 number, 1 special char
Regex: /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/Key Features & Performance
- ✓Curated pattern presets: Emails, URLs, IPv4/IPv6, Phone Numbers, Dates, Strong Passwords.
- ✓Custom pattern builder with Character Classes, Quantifiers, and Lookahead Assertions.
- ✓Live interactive test string validator with match highlighting.
- ✓Regex flag selectors: Global (g), Case-Insensitive (i), Multiline (m), DotAll (s).
- ✓100% Client-Side computation.
- ✓1-Click Copy regex pattern.
Key Terminology & Definitions
Lookahead Assertion (`(?=...)`)
A zero-length regex condition that verifies whether subsequent characters match a pattern without consuming them.
Capture Group (`(...)`)
A subpattern enclosed in parentheses that isolates matched substrings for individual extraction.