PDFAmigo - Create interactive, fillable PDF forms in your browser.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
PlatoForms - Convert PDFs to forms and let people fill them easily.
Anvil PDF Filling API - The easiest way to programmatically populate any PDF
Adobe Fill & Sign - Fill and sign any form, even snap a picture of a paper form to fill out.
KDAN Mobile PDF Reader - PDF Reader is the one app you can rely on when you need a portable solution to work with PDFs.