Available in version 3.3 or later.
You can add / edit annotations in PDF files.
aMost common annotation is highlighting of text: select text and press a. This creates a highlight annotation in yellow color:
Here I highlighted word USAGE and pressed a.
Notice in toolbar (upper right) we show: You have unsaved annotations.
When you close the document (or exit the app) and have unsaved annotations, SumatraPDF will ask if you want to save them:
If you close the dialog or choose Discard, annotations will be lost.
Save changes to existing PDF will over-write the PDF with newly added annotations.
Save changes to a new PDF will allow you to save as a new file.
If you press A (upper case i.e. Shift-a) we will create a highlight annotation (same as lower case a) but also open annotation editor window.
Another way to open annotation editor is to use context menu (right mouse click or Shift-F10) and use Edit Annotations:
