Feature

Prefill form fields from URL parameters

Add a field's ID and a value to the page URL, and Growform fills that field in when the form loads. Leads you already know something about have less to type.

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What is URL prefill?

URL prefill fills in a form field with a value taken from the URL of the page. When the URL contains a parameter whose name matches a field's ID, Growform puts the value of that parameter into the field as the form loads. It works without any setup.

You can prefill a form from a URL in an email link, an ad or a redirect from another form.

Which field types can be prefilled?

URL prefill works on the fields a lead types into, and on the slider. The full list is below.

Text
Number
Slider
Email
Zip / postal code
Phone
Website
Address Lookup, where the value prefills the address search
The legacy Address field on older forms

What is the difference between URL prefill and hidden fields?

URL prefill fills in a field the lead can see, and a hidden field stores a value the lead never sees. Prefill is for answers such as an email address, a ZIP code or a loan amount, and the parameter name must be the field's ID.

Hidden fields are for data about the visit, such as utm_source, a click ID or an affiliate ID. You choose which parameter name a hidden field looks for, and you can give it a default value. Most lead generation forms use both. Hidden fields handle UTM tracking, and prefill handles what the lead would otherwise type again.

When should you pre-populate form fields?

Pre-populate form fields whenever you hold the answer before the lead reaches the form. Three cases come up most often.

An email campaign to existing contacts can carry each contact's email address in the link.
A landing page that collects a ZIP code above the form can pass it in the URL, so the form does not ask again.
A first form can redirect to a second form with its answers in the URL.

How to prefill a field in Growform

Copy the field ID

Select the field and open its advanced settings. The read-only “External Field ID” looks like text_826111115413472.

Add it to the URL

Put the ID and the value on the URL of the page that shows the form, as in ?text_826111115413472=Denver. Join several parameters with an ampersand.

Encode the values

Values must be URL-encoded, so the @ in an email address is written as %40. Most email and ad platforms do this when they insert a value into a link.

Open the link and check

Load the page with your test URL and confirm that each field shows the value you sent.

What prefilled fields change for your completion rate

Known contacts have fewer fields to fill in.
The email address or ZIP code you already hold is in the field when the form opens.
Answers stay consistent with your records.
The value comes from your own link, so the email on the lead matches the email in your list.
Two forms can work as one journey.
The second form receives the answers from the first through the URL and shows them in its fields.
Nothing has to be installed on the page.
Prefill reads the URL, so the only thing you build is the link.

Which plans include URL prefill?

URL prefill works on every plan from the moment the form is live.

Basic: Yes
Professional: Yes
Scale: Yes
Custom: Yes

Frequently asked questions

Which parameter name does prefill use?

Prefill uses the External Field ID of the field as the parameter name. For a value you want to name yourself, use a hidden field, where you choose the parameter it reads.

Does URL prefill work when the form is embedded on my website?

Yes. The embed forwards the URL parameters of the page it sits on into the form, so the parameters go on the URL of your own page.

How do I match parameter names between two Growform forms?

Use “Send query param as...” on each field of the first form. Set it to the External Field ID of the matching field in the second form.