Annotate and comment on locked PDFs for free. Great for digital marking.
There are probably many occasions when you have been given or have found a PDF document that you’d like to be able to annotate or comment on but when you open it up in Adobe Reader you find that it appears locked and there is no way to comment on it.
Foxit Reader is an excellent free download from http://www.foxitsoftware.com/Secure_PDF_Reader/. It will allow you to annotate almost any PDF either freehand or using text boxes. With some form of tablet it makes it possible even to mark scans of handwritten work such as maths problems, and with no cost.