PDF live editing

QUESTION:

I am looking for any libraries (paid or freeware) that would allow for live pdf document editing in the browser.

PROBLEM:

Let's say I have a selection of pdf documents that represent templates. I would like to implement a functionality that would allow me to select a pdf document and enable me to directly edit it in the browser. Right now, the problem is solved by inserting text into a wysiwyg editor, and generating a document from that using a library in PHP or generating it manualy using the given pdf template, which works, but is not ideal in terms of convenience and functionality.

Thanks in advance!