Regex Builder
Pick a common regex pattern from the library, email, URL, UUID, phone, and more, then test it live.
Pattern libraryLive testClient-sideFree to use
Flags
How to use
- Pick a pattern. Library has 16 common regexes.
- Test against your input. See matches and groups instantly.
Common use cases
- Starting a regex quickly
- Learning regex patterns
- Sanity-checking a complex expression
Frequently asked questions
- Which patterns are in the library?
- Email address (RFC-5321-ish), URL (http/https), IPv4, IPv6, UUID (any version), Hex color (#fff or #ffffff), Credit card number, ISO date (YYYY-MM-DD), US date (MM/DD/YYYY), US phone number, plus a few more for common parsing tasks.
- Are these patterns production-ready validators?
- They are good-enough patterns for the common case, not strict spec validators. The email pattern matches RFC-5321-style addresses but does not enforce every edge case in RFC 5322. For mission-critical validation, use a dedicated library or send-and-verify flow.
- How is this different from the Regex Tester?
- Regex Tester is for testing arbitrary patterns you write. Regex Builder gives you a head start with proven patterns from a library, which you can then customize and test live in the same interface.
- Can I edit a library pattern after picking it?
- Yes. The library populates the pattern field; you can then tweak the regex, change flags, and test against your own input. Useful for adapting a generic pattern to your exact format.
- Does the pattern match against my data privately?
- Yes. Matching uses the browser native JavaScript RegExp engine; no input or pattern is sent to a server.
Related tools
How to use
- Pick a pattern. Library has 16 common regexes.
- Test against your input. See matches and groups instantly.
Common use cases
- Starting a regex quickly
- Learning regex patterns
- Sanity-checking a complex expression
Frequently asked questions
- Which patterns are in the library?
- Email address (RFC-5321-ish), URL (http/https), IPv4, IPv6, UUID (any version), Hex color (#fff or #ffffff), Credit card number, ISO date (YYYY-MM-DD), US date (MM/DD/YYYY), US phone number, plus a few more for common parsing tasks.
- Are these patterns production-ready validators?
- They are good-enough patterns for the common case, not strict spec validators. The email pattern matches RFC-5321-style addresses but does not enforce every edge case in RFC 5322. For mission-critical validation, use a dedicated library or send-and-verify flow.
- How is this different from the Regex Tester?
- Regex Tester is for testing arbitrary patterns you write. Regex Builder gives you a head start with proven patterns from a library, which you can then customize and test live in the same interface.
- Can I edit a library pattern after picking it?
- Yes. The library populates the pattern field; you can then tweak the regex, change flags, and test against your own input. Useful for adapting a generic pattern to your exact format.
- Does the pattern match against my data privately?
- Yes. Matching uses the browser native JavaScript RegExp engine; no input or pattern is sent to a server.