How to pass URL parameters to HubSpot contact records from a form

HubSpot 5 min read

Sometimes you want a form to already know who is filling it out, or to carry campaign information along with the submission. URL parameters make that possible. Here is how to pass values through a URL and into your HubSpot contact records using a form published with flng.ai.

What URL parameters are

A URL parameter is extra information tacked onto the end of a web address after a question mark. For example, ?email=name@domain.com or ?utm_source=newsletter. Your form can read these values and use them, either to pre-fill fields or to quietly pass hidden data along with the submission.

Why this is useful

Update the right contact. Pass a known email so the submission updates that specific HubSpot contact instead of creating a duplicate.
Track campaigns. Carry UTM values into hidden fields so you know which campaign drove each submission.
Personalize. Pre-fill a name or company so a returning visitor does not have to retype it.

Step 1: Ask your AI to read URL parameters

When you build the form, prompt your AI tool to update the HTML so it reads values from the URL and pre-populates fields or hidden inputs. A prompt like this works:

Update this form so it reads URL parameters and uses them to pre-fill matching fields. Also add hidden fields for utm_source, utm_medium, and utm_campaign that populate from the URL.

Step 2: Publish with flng.ai

Upload the updated HTML and map your fields, including the hidden ones, to HubSpot properties. The hidden fields map just like visible ones.

Step 3: Use the parameters in your links

Now append the parameters to your form's URL when you share it. For example, to make sure a submission updates a known contact, add their email:

https://your-form-url/?email=name@domain.com

The form reads that email, and on submission flng.ai identifies and updates the matching HubSpot contact rather than creating a new one.

A note on privacy

Be thoughtful about passing personal data in URLs, since URLs can be logged or shared. For sensitive updates, prefer short-lived links and avoid exposing more than you need to. For campaign tracking with UTM values, there is no such concern.

The takeaway

URL parameters turn a generic form into a context-aware one. Ask your AI to read them, map the hidden fields in flng.ai, and append the values to your links. Your submissions land on the right contact with the right campaign data attached.