Need to edit a PDF document but don’t want to pay for the more expensive Adobe editors? You can add text to and sign a PDF with just the free Reader program.

Digital signing on Android smartphones (with red color) Digital documents can also be signed on-the-go in no time at all. This is also free and easy with PDF Reader – PDF Viewer. You can ...

How to Create a Digital Signature Using PDF Security. Adobe Acrobat enables you to create PDF documents that are compatible with virtually every operating system and platform.

To password protect a PDF in Adobe Acrobat Reader, you'll need the paid Pro version, which starts at $14.99 a month.