Hidden Field

A hidden field captures data without the respondent seeing it. The value comes from URL parameters — so you can pass information like a user ID, campaign source, or referral code right through the form link.

Adding a hidden field

• Click the + button between blocks, or
• Type /hidden and select Hidden field from the list

Then give the field a name — this becomes both the label in your responses and the URL parameter key.

How it works

1. You add a hidden field named, say, source
2. You share a link like share.formgrid.com/HdNx57CuUeKzkov8?source=newsletter
3. When someone submits the form, “newsletter” gets captured as the value for the source field
4. You see it in your responses alongside all the visible field data

The respondent never sees the field — it’s completely invisible in the published form.

Settings

Click the drag handle on the left side of the field to open its settings:

• No duplicates — reject submissions whose hidden value duplicates an earlier one. Useful when the hidden field carries a user ID or invite code that should only be redeemed once. See Preventing duplicate submissions

Use cases

• UTM tracking — pass utm_source, utm_medium, etc. to track where submissions come from
• User identification — pass a user ID or email to link submissions to specific people
• A/B testing — pass a variant identifier to track which version of a page drove the submission
• Referral tracking — know who or what referred each respondent

Limits

Hidden field values can be up to 5,000 characters long. Values longer than that get truncated automatically.

Tips

• Use descriptive field names so you can easily identify the data in your responses
• You can add multiple hidden fields to track different pieces of context
• If the URL parameter isn’t present, the hidden field value will be empty in the submission