Validation

Official Docs

Defaults

First name

Last name

Username

City

State

Zip

Agree to terms and conditions

Custom

First name

Looks good!

Last name

Looks good!

Username

Please choose a username.

City

Please provide a valid city.

State

Please select a valid state.

Zip

Please provide a valid zip.

Agree to terms and conditions

You must agree before submitting.

serverSide

First name

Looks good!

Last name

Looks good!

Username

Please choose a username.

City

Please provide a valid city.

State

Please select a valid state.

Zip

Please provide a valid zip.

Agree to terms and conditions

You must agree before submitting.

Elements

Textarea

Please enter a message in the textarea.

Check this checkbox

Example invalid feedback text

Toggle this radio

Or toggle this other radio

More example invalid feedback text

Example invalid select feedback

Example invalid form file feedback

Tooltips

First name

Last name

Username

City

State

Zip

Options

Reference	Details
`How it works`	Here's how form validation works with Bootstrap: HTML form validation is applied via CSS's two pseudo-classes, `:invalid` and `:valid`. It applies to `<input>`, `<select>`, and `<textarea>` elements. Bootstrap scopes the `:invalid` and `:valid` styles to parent `.was-validated` class, usually applied to the `<form>`. Otherwise, any required field without a value shows up as invalid on page load. This way, you may choose when to activate them (typically after form submission is attempted). To reset the appearance of the form (for instance, in the case of dynamic form submissions using Ajax), remove the `.was-validated` class from the `<form>` again after submission. As a fallback, `.is-invalid` and `.is-valid` classes may be used instead of the pseudo-classes for server-side validation. They do not require a `.was-validated` parent class. Due to constraints in how CSS works, we cannot (at present) apply styles to a `<label>` that comes before a form control in the DOM without the help of custom JavaScript. All modern browsers support the constraint validation API, a series of JavaScript methods for validating form controls. Feedback messages may utilize the browser defaults (different for each browser, and unstylable via CSS) or our custom feedback styles with additional HTML and CSS. You may provide custom validity messages with `setCustomValidity` in JavaScript. With that in mind, consider the following demos for our custom form validation styles, optional server-side classes, and browser defaults.
`Browser defaults`	Not interested in custom validation feedback messages or writing JavaScript to change form behaviors? All good, you can use the browser defaults. Try submitting the form below. Depending on your browser and OS, you'll see a slightly different style of feedback. While these feedback styles cannot be styled with CSS, you can still customize the feedback text through JavaScript.
`Custom styles`	For custom Bootstrap form validation messages, you'll need to add the `novalidate` boolean attribute to your `<form>`. This disables the browser default feedback tooltips, but still provides access to the form validation APIs in JavaScript. Try to submit the form below; our JavaScript will intercept the submit button and relay feedback to you. When attempting to submit, you'll see the `:invalid` and `:valid` styles applied to your form controls. Custom feedback styles apply custom colors, borders, focus styles, and background icons to better communicate feedback. Background icons for `<select>`s are only available with `.form-select`, and not `.form-control`.
`Server-side`	We recommend using client-side validation, but in case you require server-side validation, you can indicate invalid and valid form fields with `.is-invalid` and `.is-valid`. Note that `.invalid-feedback` is also supported with these classes. For invalid fields, ensure that the invalid feedback/error message is associated with the relevant form field using `aria-describedby` (noting that this attribute allows more than one `id` to be referenced, in case the field already points to additional form text). To fix `issues with border radius`, input groups require an additional `.has-validation` class.
`Supported elements`	Validation styles are available for the following form controls and components: `<input>`s and `<textarea>`s with `.form-control` (including up to one `.form-control` in input groups) `<select>`s with `.form-select` `.form-check`s
`Tooltips`	If your form layout allows it, you can swap the `.{valid\|invalid}-feedback` classes for `.{valid\|invalid}-tooltip` classes to display validation feedback in a styled tooltip. Be sure to have a parent with `position: relative` on it for tooltip positioning. In the example below, our column classes have this already, but your project may require an alternative setup.
`Documentations`	Please visit: https://getbootstrap.com/docs/5.3/forms/validation/