Regex Searchable Reference (Common Pattern Library)
For developers, writing a regular expression from scratch is often a journey into 'regex hell'. Instead of wasting time debugging complex character classes, our Searchable Reference Hub provides a curated library of standard, battle-tested patterns. Whether you need to validate a strict V4 UUID, extract HTML tags from a string, or enforce complex password security rules, you can find and copy the exact expression you need in seconds.
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Email Address
Standard RFC 5322 compliant email validation.
IPv4 Address
Validates standard 32-bit IP addresses.
URL (HTTP/HTTPS)
Matches standard web addresses with optional protocol.
ISO Date (YYYY-MM-DD)
Matches the standard ISO 8601 date format.
Phone Number (US)
Flexible US and international phone formats.
Credit Card (General)
Matches Visa, Mastercard, Amex, and more.
Strong Password
Min 12 chars, 1 uppercase, 1 number, 1 special char.
HTML Tag
Extracts opening and closing HTML tags.
Hex Color Code
Validates 3 or 6 digit hex color strings.
Username (Alphanumeric)
3-16 chars, alphanumeric and underscores.
UUID (Version 4)
Strict validation for v4 UUID strings.
URL Slug
Lowercase, hyphen-separated permalinks.
Mastering Regular Expressions
These are 'anchors'. ^ matches the beginning of a string, and $ matches the end. Together, they ensure the entire string matches your pattern exactly.
Quantifiers! + means 'one or more' of the preceding character, while * means 'zero or more'. Use ? to make a search 'lazy' or optional.
Character sets. [a-z] matches any lowercase letter. [^0-9] matches anything that IS NOT a number. Very useful for strict filtering.
How to use this tool
- Use the visual search bar above to type what you are trying to match (e.g., 'email' or 'hex').
- Browse the results across categories like Validation, System, and Frontend.
- Each pattern includes a detailed description explaining what it actually does under the hood.
- Click 'Copy Pattern' to save the raw string to your clipboard.
- Paste the expression into your project's `.test()` or `.match()` function.
Example Usage
Search: "IPv4"
Pattern: ^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}...When to use this tool
- Frontend developers building form validation logic for emails, passwords, and phone numbers.
- Data engineers extracting specific fields (like ISO dates or colors) from large log files.
- Backend developers enforcing strict input constraints on API endpoints (e.g., UUID validation).
- A11y/UI testing where you need to verify if strings follow specific structural patterns.
Frequently Asked Questions
Are these regex patterns JavaScript-compatible?
Yes. All patterns in this library are written to be compatible with standard PCRE and JavaScript RegExp engines. For use in Java or Go, you may occasionally need to double-escape backslashes (e.g., \\d instead of \d).
Can I test these patterns with my own data?
Absolutely. We recommend using our 'Regex Match & Extract' tool to paste these patterns into a live tester where you can see how they highlight your actual test strings in real-time.
What does the 'Validation' category mean?
Validation patterns are designed to return a true/false match for a specific format. They typically start with ^ and end with $ to ensure the entire string conforms to the rule.
Are these patterns officially 'Perfect'?
Regex is a trade-off between strictness and usability. For example, our email pattern covers 99.9% of standard web usage, but RFC-compliant email validation is notoriously complex. These are designed for real-world production reliability.
Is this tool updated regularly?
Yes, we continuously add new patterns based on the highest-volume search queries we see in our logs, ensuring the database stays relevant for modern framework development.