PDFill is not available for Linux but there are plenty of alternatives that runs on Linux with similar functionality. The best Linux alternative is PDFsam, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to PDFill and 16 are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to PDFill are PDF Arranger (Free, Open Source), Master PDF Editor (Freemium), PDF Studio (Freemium) and PDF-Shuffler (Free, Open Source).
Aspose.Pdf for Cloud is a REST API to create, edit & manipulate PDF files. It also convert PDF file to DOC, DOCX, HTML, XPS, TIFF etc. You can create a new PDF either from scratch or from HTML, XML, template, database, XPS or an image.