Retrieve a list of browsers/agents installed in client system
Short answer: No, it is not possible
Long answer: This is something that any sane (operating) system designer / administrator would  try to prevent - scanning of local system by a web page. However, you could use a plug-in component, such as a java applet, to do so - but in practice you probably would need to handle each client platform (OS) separately, since each of them has a different way of storing the information of installed software
I would like to write a web application (in django) which scans the client/remote computers (assumption is windows) and retrieve the list of software's(mainly browsers) installed. Looking for suggestions to implement it.

Is this possible without asking the user to download any scritps/exe's?
If so, is it possible via java script?

I am planning to use python/django to write the entire app. Any input would be much appreciated.
EDIT : Comments on feasibility in java also much appreciated