Contact Form Validation: Options for Checking User Data (Updated 2026)

Once upon a time, this blog post said that “contact forms are great,” but now in the updated 2026 version, we want to stress that contact forms are essential. Like, required. Totally not optional. What are you doing with your life if you don’t have a contact form on your website?

Contact forms allow businesses to receive information from potential clients at any time of the day, at the user’s convenience. Every business is a bit different, but for PaperStreet, for every phone call we receive for a new client, we receive about one form too. So it is a 1:1 ratio. We work with 100s of law firms on a monthly basis, and as a general statement, that seems to be a fair estimate of the truth for them as well.

Since we have used contact forms for over 25 years now, we have experience with spam inquiries and how to prevent them. There are a few core ways to validate your form: (1) required fields, (2) check user input (3) honey pot (4) CAPTCHA, and (5) real time lookup.

Required Fields

The first step in form validating is simply making sure that required fields are filled out. We always recommend that the name, phone and email be filled out and “required.” The extra step of making these fields mandatory will prevent general spam bots from hitting the form and sending blank emails. It makes it at least that much harder for them to spam.

Check User Input

The next step is to check user input. Often spam bots want links, so the easiest thing to do is prevent any link code from being put into any field, which includes HTML code, JavaScript code or anything that may be malicious. We recommend you run a query before you submit the form and if any suspicious HTML code is present, then stop the form and display an error. These type of validation checks stop almost all spam. We have seen a high success rate using this tactic.

Honey Pot

Another awesome validation check is to put in extra form fields that are hidden from a real user on the page, but a bot would actually see them. If the bot sees the field it will most likely fill out that form field with information. Since you created the form, you then know the form field should not have anything completed, which allows you to flag it as spam. Now this solution won’t prevent you from getting spam, but it can help you determine what leads are most appropriate and save you time reaching out to junk calls.

CAPTCHA

There are tools like CATPCHA to prevent more spam. If you have used the internet for more than a day, you’re familiar with how these work. CAPTCHA requires the user to repeat a set of letters/numbers before they click send/submit. However, we do not recommend installing a CAPTCHA, as the are simply barriers to having legitimate users fill out the form. Don’t get us wrong, CAPTCHAs have their place, but often they are overkill for most forms and since they could hurt conversion rates we approach this solution lightly.

Real Time Lookup

Finally, there are great tools and APIs that take the user input of name, email, or phone of the form and check that against a database of known information to see if they are real. These services require type to setup and integrate into your email process, but can prevent further spam and give you detailed information about your potential customer.

Phone Validation

Note: These are in no particular order.

• https://www.edq.com/phone-validation/
• https://www.twilio.com/lookup
• https://numverify.com/
• https://www.nexmo.com/products/verify/
• https://datafinder.com/api/overview
• https://www.fullcontact.com/developer/
• …and there are others. (If you want your company listed, let us know.)

Email Validation

Note: These are in no particular order.

• http://www.briteverify.com/
• https://mailboxlayer.com/
• http://emailpie.com/
• https://documentation.mailgun.com/api-email-validation.html
• http://verify-email.org/
• http://www.xverify.com/email-verification-signup.html
• https://www.email-checker.com/
• https://kickbox.io/
• https://www.emailhippo.com/en-US
• https://neverbounce.com/
• https://datafinder.com/api/overview
• https://www.fullcontact.com/developer/
• …and there are others. (If you want your company listed, let us know.)

Key Takeaway: A Dose of Prevention is Worth a Shot

Finally, please note that no system is perfect. We recommend a layered approach and start with requiring fields and checking user input. See what happens and if you feel like you need extra support, install a honey pot, then CAPTCHA and finally, if spam is a big issue, do real-time lookups. Does this all sound like it’s too much for your doing? The PaperStreet Help Desk can assist if you feel your contact form is generating too much spam. Reach out to our team today and see what we can do to help clean up your leads via contact form.