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How to Prefill a Signup Form With User Information - SMASHSEND

/referral-marketing/guides/prefill-signup-forms-with-user-information

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Words
317
Reading time
1 min
Published
2023-02-22
Last crawled
2026-09-27
Language
EN
A1

Opening

Availability: field prefilling is rolling out. The URL format below is the one it will use, so links you build now keep working once it is live. If you already know who someone is, you should not make them type it again.

A2

The URL format

Add a query parameter for each field you want to fill. The parameter name is the field key, which you can find next to each field in the form builder. Anything you do not pass is simply left blank. The person can still e

A3

Encode your values

Query strings cannot contain raw spaces, ampersands or plus signs, so URL-encode every value you interpolate. In JavaScript:

A4

Prefill from an email

Inside a SmashSend email you can build the link with contact properties, so each recipient gets their own prefilled form:

A5

Reserved parameters

Two parameter names are reserved and are not treated as fields: - tracks who referred this signup. It is set automatically on the share links your referrers get, so do not overwrite it. - unlocks a password-protected for

A6

A word on trust

Anything in a URL can be edited by the person opening it, so treat prefilled values as a convenience rather than as verified data. If you need to be certain who submitted a form, confirm it on your side, or turn on doubl

A7

Have questions?

If you get stuck, email support@smashsend.com or contact us.

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