Php pdf editing

I want to know can I modify an existing pdf file in php ?

I’ve a pdf file which have some field to be filled in.

I want to fill those fields through php. Is it possible to do through php ?

if yes, then please guide me.

Thanx.

Never tried it myself, but http://www.setasign.de/products/pdf-php-solutions/setapdf-formfiller/ seems like a place to start.