Input Validation Regex

Build validation rules for input fields

Validating user input is a security and quality essential, and getting the rules right, especially regex, is fiddly. This tool generates regex and validation rules for input fields, so you can constrain input correctly without hand-crafting patterns.

Why input validation is critical

Unvalidated input is the root of many security problems and countless bugs, because code that assumes input is well-formed breaks when it is not. Validating that a field matches its expected format, an email, a phone number, a specific pattern, rejects bad input at the boundary before it causes harm. But writing correct validation, particularly regular expressions, is notoriously error-prone. Generating the rules and patterns for common field types gives you correct validation to apply, which is both a quality and a security measure. Server-side validation remains essential even with client-side rules.

Constrain input correctly

It runs entirely in your browser, so nothing you paste is uploaded and the result is yours to copy straight into a project. Because it works client-side, you can use it on private code and data without anything leaving your machine.

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