Dev
Common Regex Pattern Generator
Common validation patterns — emails, URLs, phone numbers, dates, hex colours, slugs — are written repeatedly across codebases, often from memory, and small errors in anchoring or character classes cause validation bugs that are hard to catch. This generator returns a ready-to-use regex pattern for one of six common validation targets along with a plain-English explanation of exactly what the pattern matches and what it does not. The pattern for dropdown selects the target: email uses a practical basic pattern that checks for characters, an @, a domain, and a dot-TLD; url matches http or https URLs; phone covers international-style numbers with optional separators; date matches ISO 8601 YYYY-MM-DD format; hex color matches 3- or 6-digit hex codes with a leading #; slug matches lowercase alphanumeric URL slugs with hyphen separators. Random draws from all six. Each result shows the pattern string and a description of what it matches. Before using a pattern in production, test it against real inputs and known edge cases for your specific use case. Each pattern is a practical starting point — email patterns in particular are intentionally simple rather than exhaustively spec-compliant, which is the right trade-off for most applications.
How to use
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Choose what you want to match, or leave it on random.
- Click Generate to get a pattern and its explanation.
- Copy the pattern into your validation code.
- Test it against real and edge-case inputs before relying on it.
Use Cases
- •Validating emails, URLs, phone numbers, and dates
- •Starting from a tested pattern instead of writing from scratch
- •Learning how common regex patterns are built
- •Documentation and code-comment examples
- •Quick reference when you forget a pattern
Tips
- →Always test a regex against edge cases, not just the happy path.
- →Mind escaping — some languages require backslashes to be doubled in strings.
- →For emails, a simple format check plus a confirmation email beats a perfect regex.
- →Anchor patterns with ^ and $ when you mean to match the whole string.
FAQ
what is a regular expression
A regular expression, or regex, is a pattern that describes a set of strings, used to search, match, and validate text. For example, an email regex checks whether a string has the shape of an email address. Regex is supported in virtually every programming language.
is there a perfect email regex
No — fully validating every legal email address by regex is famously impractical, since the official specification is extraordinarily permissive. A simple pattern that checks for characters, an @, and a domain catches the vast majority of mistakes; for true verification, send a confirmation email.
how do I use these patterns in my language
Most languages have a regex engine with similar syntax. Paste the pattern into your language's regex constructor or literal, mind any escaping rules (some languages need backslashes doubled in strings), and test it against real examples before relying on it.
does the generator anchor patterns to match the whole string
The email pattern uses ^ and $ anchors to match the full string. The URL pattern also uses ^ and $. The phone, date, hex color, and slug patterns use similar anchoring. Always verify anchoring behaviour for your specific use case — some engines require anchors, others treat patterns as substring searches by default.
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