1. A method performed by a computing device, the method comprising: receiving, by the computing device and over a computer network, form data that specifies characteristics of an electronic form, the form data including one or more rules configured to vary content of the electronic form that is presented for different users, wherein the form data specifies a data type for user input collected through the electronic form, the data type representing a user attribute for a user completing the electronic form; obtaining, by the computing device, user data indicating (i) characteristics of the user specified by a user profile, and (ii) activities of a user relating to electronic forms previously provided to the user on the computing device; selecting, by the computing device, an interactive element to receive user input of the specified data type, the interactive element being selected based on the characteristics of the user, the activities of the user, and the rules in the received form data, wherein the interactive element is selected from among multiple different interactive elements that each receive user input of the specified data type, wherein each of the multiple interactive elements is configured to provide a measure of the user attribute at a different level of precision; customizing, by the computing device, a view of the electronic form for the user of the computing device by including, in the customized view, the interactive element selected based on the user data and the rules in the received form data; and displaying, by the computing device, the view of the electronic form that is customized for the user of the computing device.