The answer to a boolean question is stored as the boolean true or false.

{
  "my_boolean": true
}

A boolean question may take any of the styles of the select question; it defaults to displaying as buttons.

Changing the labels

The boolean question only has two choices, "Yes" and "No".

If you'd like to change the labels of those choices, you can do so in the choices tab.

Adding more than two choices

If you'd like to have more than two choices mapped to true or false, use a select question and change Choice value type to boolean.