Prefill form fields with URL parameters

Open a form with fields already filled in by adding values to the link. Useful for pre-filled requests, quick demos, and quietly passing tracking data along with a submission.

How it works

Add one or more data. parameters to the end of a form's link. Each one fills a single field with the value you provide:

https://app.droplet.io/form/<formId>?data.<fieldId>=<value>

Chain several together with & to prefill multiple fields at once:

https://app.droplet.io/form/yGwOVy?data.submittedByName=Jane%20Doe&data.department=Finance

When someone opens that link, the form loads with those fields already populated. They can still edit any field that is visible and editable before submitting.

Prefilling a field that drives Show/Hide rules or a computed value makes the form reshape on load. It is the fastest way to demo a specific path, or to hand someone a request that is already most of the way filled out.

Find a field's ID

Each data. parameter targets a field by its ID, not its label. To find a field's ID, open the form in the Form Builder, select the component, and look under Details in the Properties panel. Use that exact ID in the link.

Every form has built-in submittedByName and submittedByEmail fields, so links like ?data.submittedByName=Jane work on any form.

Format the values

URL-encode the value: Spaces become %20, and other special characters need encoding too: & → %26, / → %2F, @ → %40, , → %2C, ( → %28, ) → %29. Most spreadsheet and scripting tools have an "encode URL" function that does this for you.
Match choices exactly: For a Dropdown or Single Choice field, the decoded value must match one of its options exactly. For example, data.paysheetType=Time%20%26%20Attendance sets the option "Time & Attendance."
Dates use YYYY-MM-DD: A Date/Time field takes an ISO date, like data.startDate=2026-09-01.

Pass hidden data with a submission

Here is the useful trick: prefill a field through the link, then hide that field on the form. The submitter never sees it, but the value is still saved with their submission. It is a clean way to tag where a submission came from (a campaign name, a referral source, a routing code, or an internal reference) without cluttering the form.

Add a field for the value

Add an Input (or other field) for the data you want to capture, and note its ID.

Hide it

Set the field's Visibility to Hidden, or add a Show/Hide rule that keeps it hidden. Leave the field's "clear when hidden" option off, otherwise the prefilled value is wiped when the field hides.

Share the link with the value baked in

Distribute a link like ?data.source=spring-newsletter. Each submission from that link records "spring-newsletter" in the hidden field.

This data is "hidden," not secret. The value is part of the link, so anyone who has the URL can read it, and a determined submitter could inspect the page. Use it for routing and source tracking, never for passwords, tokens, or anything that would be sensitive if seen.

Prefill a draft while testing

To prefill an unpublished draft while you are building, add preview=true and the draft's version before the data. parameters:

https://app.droplet.io/form/<formId>?preview=true&version=draft-<timestamp>&data.<fieldId>=<value>

Things to know

Tables aren't prefillable. Table rows and columns are list fields and don't reliably accept simple data. parameters, so leave those for live entry.
Sign-in can override the submitter fields. If a form requires sign-in or submits as the signed-in account, the logged-in person's name and email replace any prefilled submittedByName / submittedByEmail.
Links change when the form is re-saved. A draft's version (and sometimes the form ID) updates when you save or re-import, so refresh your test links after changes.

Looking for other ways to get a form to people? See Share a form link and Use the Forms page.

Last reviewed by Nick Duell and published on June 22, 2026 10PM ET