How to add some text in an existing PDF document e.g. for revision

If you have to add some text in an existing PDF document e.g. for revision you can use this web-tool:

http://www.pdfescape.com/

It's free and very simple.

1. Upload your document
2. Edit your document
3. Download the finalized document

But, please be aware, that you only can add text. It's not possible to remove existing text. 

Have fun!