Contact Form 7 – Conditional Fields Pro
This plugin adds conditional logic to Contact Form 7. If you edit the CF7 form, you will see an additional tag “Group of conditional fields”. Everything that you put between the start and end tags will be hidden by default. After you have added the group (s) of fields, click “Save” and go to the tab “Conditional fields” to create one or more conditions that will lead to the appearance of the group (s).
