Official repository of the bootstrap_form gem, a Rails form builder that makes it super easy to create beautiful-looking forms using Bootstrap 4 -bootstrap_form is a Rails form builder that makes it super easy to integrate Bootstrap v4-style forms into your Rails application. It provides form helpers that augment the Rails form helpers. bootstrap_forms's form helpers generate the form field and its label and all the Bootstrap mark-up required for proper Bootstrap display. bootstrap_form also provides:.