fillable-pdf

FillablePDF is an extremely simple and lightweight utility that bridges iText and Ruby in order to fill out fillable PDF forms or extract field values from previously filled out PDF forms. Maintained by vkononov on GitHub, where it has earned 80 stars from the community.

It's actively developed around fillable-pdf, itextpdf, ruby-on-rails, and is a solid reference for anyone building with these tools.