What is a good freeware PDF editting application?

I'm looking for an application to edit PDF's so I can make dungeons and dragons character sheets on my computer. The sheets are in PDF format, so all I really need to do is add text, but all the editors I find are stiff web based programs or trial versions that limit tools, don't allow saves, or add an obnoxious watermark. And good FREE applications? Not really willing to shell out sixty bucks for a table top RPG.