jPDFViewer - Use jPDFViewer Java PDF SDK to integrate a PDF reader right into your Java application or website.

Usersnap - Visual Feedback - Usersnap helps your business with its versatile feedback platform to build better, more successful products and services with the help of user feedback. Collect feedback along your product development lifecycle. Try it for free.

MuPDF - MuPDF is a lightweight PDF and XPS viewer.

Tweakr.io - The fastest way to get visual feedback 📌

Altarsoft PDF Reader - Altarsoft PDF Reader is a simple to use PDF files management program that allows its users to view PDF files, encrypt the files and even annotate these files as well.

Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.