Browser items entry script

I need a script working in Windows or Mac to recognize items in open browser. It should read objects in the browser and make/change the entries there. If it cannot recognize open browser, it should make changes in registry to make it work. For example, you have a listing or post with multiple inputbox and radio buttons. A script should get parameters from text file and make an entry into those input boxes accordingly. A browser preferably be Chrome but some of the scripts work only in specific so can be any. I'm doing this on Autoit but probably you have better way or you can make it more robust. Please don't ask me for money until you show me what you have.