Regex Generator

1. Select a Use Case: Choose from categories like Contact Information, Web & URLs, Network, Date & Time, Validation, Financial, or Text Patterns. Each generates a specialized regex pattern.
2. Configure Options: Some patterns offer customization—strictness levels, optional components, or format variations. Adjust settings to match your specific requirements.
3. Review the Pattern: The generated regex appears with an explanation of what it matches. Test it against sample inputs to verify it catches valid cases and rejects invalid ones.
4. Copy and Use: Copy the pattern for use in your code. Remember to adjust flags (g, i, m) based on your needs—case-insensitivity, global matching, multiline mode.

Generated patterns balance strictness with practicality. Email patterns follow simplified RFC 5322, matching common addresses while rejecting obviously invalid ones. URL patterns handle http/https, optional www, paths, and query strings. Phone patterns accommodate various formats—with or without country codes, spaces, dashes, or parentheses.

Date patterns validate format structure but can't fully validate calendar logic (regex can't know February has 28/29 days). For strict validation, use regex for format checking, then parse with a date library. IP address patterns validate octet structure and ranges. Password patterns check for required character types (uppercase, lowercase, digits, symbols) and minimum length. Each pattern is tested against common valid and invalid inputs before inclusion.

• Over-Relying on Regex for Validation: Regex validates format, not semantics. An email matching the pattern might not exist. A credit card matching the format might fail Luhn check. Use regex as a first filter, then validate with specialized libraries or APIs.
• Anchoring Issues: Most generated patterns include ^ (start) and $ (end) anchors for full-string matching. If you need to find matches within larger text, remove the anchors. Without anchors, "email" pattern would match email addresses embedded in prose.
• Locale-Specific Patterns: Phone numbers, postal codes, and dates vary by country. The US phone pattern won't match UK numbers; the US date pattern (MM/DD/YYYY) conflicts with EU format (DD/MM/YYYY). Choose the correct locale pattern.

Have an existing regex you need to understand? Use our Regex Explainer for plain English breakdowns. For a library of tested patterns, browse the Regex Pattern Library.