Populate hidden fields with Mailchimp

Mailchimp offers variables or merge tags to include all kinds of dynamic or personalized information in your email campaign. When you insert a merge tag into your campaign, Mailchimp will replace the tag with the content stored in the corresponding audience field.
Just like you would customize the name of respondents in your email campaigns, you can also customize hidden field parameters in a Tally form URL. This allows you to pass contact information from Mailchimp to your Tally form without having to customizing each form URL manually.
This guide was made with the help of Ernesto Mandowsky, founder of CPD Advisors.

How it works

1. Create a Tally form

Create a Tally form and type /hidden to insert the hidden fields you need. In this example we want to include the email address and the source of the respondent.
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Publish your form and go to the Share tab to copy the form URL.

2. Create a Mailchimp campaign

Create a campaign and embed a Button in your email. In the Link to: Web address field add the form URL including the hidden field URL parameters.
The first hidden field should be preceded by ? . When adding multiple fields, separate them with & . For example: https://tally.so/r/31eJL3?email=*|EMAIL|*&source=email
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In this example we match the hidden field ‘email’ to the email merge tag in Mailchimp (*|EMAIL|*), and the hidden field ‘source’ gets the fixed value ‘email’ (because the source of all respondents will be email).

3. Launch the campaign

When you launch your email campaign the Tally form URL will be automatically updated with the content in the corresponding audience field, and the hidden field values will be available in your Tally form results.
You can also use the hidden field values to pre-populate answers in your form