novalidate

Novalidate is a boolean attribute of the HTML form element that disables HTML5 constraint validation for that form. When present, the browser does not automatically validate controls (such as inputs with required, type, or pattern constraints) on form submission, and it will not display the built-in validation UI.

This attribute is commonly used when a page relies on custom client-side validation or when the form is submitted via JavaScript (for example, with Ajax) and validation is handled in a different way or on the server side. It does not remove the constraints from the controls themselves, nor does it prevent developers from performing validation programmatically through the Constraint Validation API.

Developers can still use JavaScript to check validity or provide custom feedback. Methods such as form.checkValidity() and control.checkValidity() can be used to assess validity, and reportValidity() can be invoked to show custom or alternative validation messages as needed. This allows teams to implement their own validation flow while opting out of the browser’s built-in validation UI on submission.

Usage is straightforward in markup and scripted form handling. In markup: <form action="/submit" method="post" novalidate>. The attribute can be added or removed dynamically via scripting (for example, form.setAttribute('novalidate', '') or form.removeAttribute('novalidate')) to enable or disable native validation as required.

Compatibility is broad across modern browsers; novalidate is part of standard HTML5 form behavior.