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Rule set is empty
Configure a field and click Add Field to Set// build form validation rules without writing regex
Build validation rule sets for text, email, password, phone, and custom fields. Export to JavaScript, PHP, or JSON schema. Free, browser-based, no sign-up required.
Rule set is empty
Configure a field and click Add Field to SetSelect from Text, Email, Password, Phone, URL, Number, Date, or Custom.
Set required, min/max length, patterns, and custom error messages for each rule.
Use the live tester to verify, add to your rule set, then copy JS, PHP, or JSON Schema output.
The Form Validation Rule Builder lets you create complete validation rule sets for web forms without writing repetitive regex or validation logic. Configure field types, constraints, and custom error messages, then export production-ready code for JavaScript, PHP, or JSON Schema.
The builder supports Text, Email, Password, Phone, URL, Number, Date, and Custom (regex) field types. Each type comes with sensible defaults you can override.
You can export your validation rule set as a JavaScript object (ready for use with native JS or libraries like Yup/Zod patterns), PHP associative array, or JSON Schema (compatible with OpenAPI, AJV, and similar tools).
Yes. Every rule — required, minLength, maxLength, pattern, etc. — has an optional custom error message field. If left blank, a sensible default is used in the export.
Yes. The Password field type includes toggles for requiring uppercase letters, lowercase letters, numbers, and special characters, plus minimum/maximum length controls.
Absolutely. Configure each field, click "Add Field to Set", and the rule set builds up. All fields appear in the output simultaneously so you can copy the entire form's validation in one go.
Custom regex patterns are validated in the browser before being added to the rule set. However, always test your patterns thoroughly — especially for edge cases and catastrophic backtracking.
As you type into the test input, all configured rules are evaluated in real-time. Each failing rule is listed with its error message so you can refine your configuration immediately.
No. All validation logic and code generation happens entirely in your browser. Nothing is uploaded or stored — this tool is 100% client-side.
A form validation rule builder is a visual tool that lets developers define and export input validation constraints without writing repetitive validation code from scratch. Instead of manually crafting regex patterns, error message strings, and conditional checks for every form field, you configure your rules through a structured UI and get clean, production-ready code in the format your stack needs.
This tool supports the eight most common field types found in web forms: plain text, email addresses, passwords, phone numbers, URLs, numbers, dates, and fully custom regex-based fields. For each type, relevant validation options are automatically surfaced — so a password field exposes character complexity rules, while a number field shows min/max value constraints.
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Form validation is one of the most critical — and most neglected — parts of web development. Poor validation leads to corrupted database entries, security vulnerabilities, and frustrating user experiences. Good validation communicates clearly to users what went wrong and prevents bad data from ever reaching your server.
The challenge is that validation must often be implemented in multiple places: in the browser for immediate user feedback, on the server for security, and sometimes in API documentation as JSON Schema. Keeping these in sync manually is error-prone. A shared rule set definition exported to multiple formats helps maintain consistency across your stack.
Text fields support required, minimum length, maximum length, and pattern matching. These cover the broadest range of inputs including usernames, names, addresses, and any free-form text.
Email fields apply RFC 5322-compliant email format validation along with optional length constraints. The default pattern catches the vast majority of valid email addresses.
Password fields are the most complex. Beyond length constraints, they support requiring uppercase letters, lowercase letters, digits, and special characters. You can combine these to enforce any password policy your security requirements demand.
Phone fields support configurable format options including international E.164 format and common local formats. Custom regex is available for country-specific patterns.
URL fields validate both HTTP and HTTPS URLs with optional protocol enforcement. Useful for link inputs, website fields, and API endpoint configuration forms.
Number fields support minimum value, maximum value, and integer-only constraints. Helpful for age inputs, quantity selectors, and score fields.
Date fields validate ISO 8601 date format and optionally enforce date range constraints with min and max date values.
Custom fields accept any regular expression pattern along with a human-readable description of what the pattern matches. This covers specialized inputs like postal codes, product SKUs, employee IDs, or any domain-specific format.
The JavaScript export produces a plain object mapping field names to arrays of validator functions or rule objects. This format is compatible with manual validation loops and can be adapted to work with libraries like Formik, React Hook Form, or custom validation utilities.
The PHP export generates an associative array suitable for use with Laravel's Validator, Symfony's Validator component, or any custom PHP validation layer. Rules are expressed in a format consistent with popular PHP frameworks.
The JSON Schema export follows the JSON Schema Draft-07 specification. This format is directly usable with validators like AJV in Node.js, the jsonschema library in Python, and any OpenAPI 3.0 specification that defines request body schemas. It's the most portable format across languages and tools.
Always validate on both the client and the server. Client-side validation provides immediate feedback and improves UX, but it can be bypassed. Server-side validation is your last line of defense and must never be omitted.
Write clear, actionable error messages. "Invalid input" is useless. "Password must be at least 8 characters and include one number" tells the user exactly what to fix. Every rule in this builder has a custom message field specifically because vague errors erode user trust.
Don't over-validate. Excessively strict rules for fields like names (which may contain accents, hyphens, or spaces) or phone numbers (which vary enormously by country) create friction without security benefit. Use the minimum constraints necessary for your use case.
Test your validation rules with real-world edge cases: empty strings, whitespace-only input, extremely long strings, Unicode characters, and SQL/HTML injection attempts. The live tester in this tool helps catch obvious issues quickly.
The rule sets generated by this tool are starting points. Copy the output, paste it into your project, and adjust the structure to match your framework's expected format. Most validation libraries have slightly different APIs, but the logical rules — required, minLength, pattern — translate directly.
For teams, defining validation rules in JSON Schema and committing that schema to your repository creates a single source of truth. Frontend and backend engineers can both reference and generate validators from the same schema, reducing inconsistencies between layers.