Foxit Reader is a lightweight, fast PDF Reader.

Nitro Software, Inc. develops commercial software used to create, edit, sign, and secure Portable Document Format (PDF) files and digital documents.

jPDF Tweak is a Java Swing application that can combine, split, rotate, reorder, watermark, encrypt, sign, and otherwise tweak PDF files.

Adobe Acrobat Reader DC is the industry standard for viewing, printing, signing and commenting on PDF documents.

Xodo is a PDF reader and annotator.