I am learning the basics of form pdfs now. After entering the field values, I can save the pdf with data as a pdf file. With Acrobat pro, I am able to export data in FDF and XFDF files. we need to develop a website that will allow users to fill a few form pdfs in browser and download it preferably as pdf forms filled with data. The PDFTron is a good solution, but it looks like I can download FDF file or XFDF file or the flattened pdf from it. The user should be able to modify the downloaded forms. Is this possible with PDFTron?
If it is not PDFTron, Is there any other way I could do this?
Yes, PDFTron fully supports online form filling and the export/import of XFDF data. In particular the WebViewer technology sounds like the best fit for you. It comes with out of the box form field filling, and XFDF is uses as the data interchange. A simple call in javascript to AnnotationManager.exportAnnotations() will give you all the form field data that you can use with any XFDF compliant PDF SDK.
This is the online sample for form filling. It will work on any modern browser/device. https://www.pdftron.com/webviewer/demo/samples/forms/index.html?doctype=xod
This presentation explains WebViewer technology at a high level. https://prezi.com/view/Aug5ft1twZNNKfBXfTIQ/
Finally, this page shows the basics of form field data interchange. https://www.pdftron.com/webviewer/demo/tutorials/getting-started-annotations.html