LinPDF

LinPDF is a simple PDF editor that lets you split and merge documents with ease. Also, it allows you to annotate and read PDF files easily.

Thus, you can add highlight, strikeout, and underline to PDF. Also, you can add various shapes, text, stamps, watermarks and pictures to PDF. You can create various styles of signatures and add them to PDF files. The tool supports encrypted PDF files and allows you to set operation permissions.