Form Validation — Importance, Ways & Best Practices

Have you ever tried filling out a form and not gotten the desired results?

Many forms are not designed properly, making the user feel lost or not knowing exactly what happened. This is where form validation comes into play.

It helps to design intuitive and responsive forms and tell the user precisely what went wrong. When forms are well-designed and simple, users are more likely to fill them out without any errors.

So in this article, we will understand what form validation is, how to implement it, and review some form validation best practices guaranteed to increase sign-up form conversions.

Let’s begin!

Form validation is the process of making sure that the data submitted through web forms is accurate, consistent, and conforms to specific rules and requirements that are predefined. If these requirements are not met, or the data is not correctly filled out, the form data will not be accepted or stored on the server.

Since it stops users from filing wrong data or prevents malicious entities from filling in harmful code or viruses via forms, it acts as the first line of defense for businesses against erroneous data entry, malicious users, and spam.

Form validation covers a few fundamental aspects, including:

The form validation process also covers insights that help improve user interaction and enhance overall user experience. For example, if you have a product page and the user has to fill in a few details during checkout, form validation processes ensure this is error-free, simplified, and quick.

The form validation process can be done using a variety of methods, but the most popular ones include:

Before submission validation is performed on the user's device before the form is submitted. Since this type of submission happens as the user fills out the form, it is also known as inline validation. It is typically done using JavaScript.

Inline validation works by continuously monitoring user input. When a user enters data into a field, the validation process assesses that input against predefined rules or patterns. If the input is correct, no feedback is provided.

However, if there's an error, such as an invalid email address, the system immediately highlights the issue and provides feedback, often in the form of error messages.

This has great benefits for user experience, such as:

However, it lacks when it comes to more complex validation such as malicious code injection into forms.

After submission, validation processes all the data once the user submits the form. It is typically done using a programming language such as PHP or Python.

It examines the entire form, checking for errors, missing information, or invalid entries after the data is submitted. If any issues are identified, it generates error messages and provides feedback to the user. Users can then make corrections and resubmit the form.

Thus, the benefits of this methodology are:

However, it lacks user experience. It can lead to latency in the form submission process, as users only know what is wrong after they hit submit. It can also be a bit frustrating to go through the form again to find and fix the errors (especially if it is a long one).

The best way to implement form validation is to look at the benefits of both methods and implement those that are ideal for your needs.

Since providing a good user experience is also very important for every business, we recommend-

✔️ Using inline validation on web forms ( like sign-ups, subscriptions, lead generation, etc.) to make it easy for the users.
✔️ Implementing after-submission form validation for payment pages that need better security.

To implement inline form validation using JavaScript, you will need to write some code to check the validity of the user input. This code can be as simple or as complex as you need it to be.

For example, the following code checks to make sure that a required field is not empty:

Once you have written your validation code, add it to your form. You can do this by adding it to the section of your HTML document or by adding it to a JavaScript file and then referencing that file in the section of your HTML document.

Several third-party libraries can be used to implement inline validation. These libraries typically provide a pre-written set of validation functions that you can use in your form.

One popular third-party library for inline form validation is jQuery Validate. To use jQuery Validate, you must include the jQuery and library on your web page. Then, you can use jQuery Validate to add validation to your form fields.

For example, the following code uses jQuery Validate to add validation to a required field:

JavaScript$(document).ready(function() { $("#required-field").validate({ required: true }); });

Once you have added validation to your form fields, you must submit the form using the submit() method. jQuery Validate will automatically validate the form fields before the form is submitted. JQuery Validate will display an error message if any form fields are invalid.

Clearout Form Guard offers real-time validation for critical user information such as email address and phone number.

Form Guard is a lightweight validation layer that integrates with any form — be it on WordPress, Webflow, Unbounce, Leadpages, or a custom no-code builder — and instantly checks every entry as the user types.

The tool offers 99% data accuracy and validates:

This means no more fake emails, burner phones, or gibberish names entering your database and skewing your analytics or clogging your CRM.

Here’s how you can integrate & use Form Guard:

Form Guard is trusted by 100,000+ forms globally and protects millions of sign-ups each day. Unlike most form plugins that check only for “required” fields or basic formatting, Form Guard goes deeper:

Here’s what Form Validation looks like with and without Form Guard.

Marketers
Stop wasting budget on fake leads from Facebook, Google Ads, or webinars. Form Guard ensures every dollar spent captures a real contact.

Sales Teams
Improve lead quality before reps even touch the CRM. Say goodbye to invalid phone numbers, unreachable names, and demo requests from bots.

Founders & No-Code Builders
Deploy an enterprise-grade verification layer on any sign-up form — no dev team needed. Perfect for early-stage startups and SaaS products.

There are a few things you should avoid when creating forms.

Sometimes, designers and form creators tend to put in too much information, making the form seem complex. Ensure that the form is concise and that you provide only the relevant information.

When it comes to errors, it is important to tell users exactly what went wrong. Providing error messages that are vague, unhelpful, or overly technical can confuse users, leaving them unsure of how to correct their input.

If the user fills out multiple incorrect fields, the form validation must clearly mention what went wrong and which fields require fixing. For example, if you have a B2B offering and want to set a requirement to allow only business emails, this can be easily achieved.

With the 20+ validation checks and customizable settings offered by Clearout, you can allow specific addresses to enter your form, remove unwanted sub-addresses (Gmail, Yahoo, AOL, etc.), identify fake emails, and do much more to ensure good data quality.

Once a user has made a mistake on your form, don't make them start over. Instead, allow them to correct their mistakes and submit the form. Starting from scratch, especially in a long-form, can be frustrating and off putting.

Every form is a chance to impress your users and showcase how your brand stands out from the rest. Here’s a cheat sheet to design forms that convert:

While designing forms, ensure the need is clear and you know what is expected. The ideal thought process should be to be concise, precise, empathetic, and flexible.

By following these tips and principles, your forms can be user-centric, making the entire form-filling experience seamless. With inline validation and advanced email verification processes, you can even fine-tune forms to be highly specific to your requirements.