.BSA file extension

This is the basic program to work with .BSA extension

Oblivion mod manager

Oblivion mod manager BethesdaSoftworks Archive

This is a utility for managing plugins, and also for packing them for distribution. It can be used either as an enhanced version of the oblivion launcher's data files selector, or as a more advanced mod manager when mods are specially packed into omod files... (more)

The program works with the following extensions: bsa, omod

.BSA extension is also supported by the following program:

Dragon UnPACKer

Dragon UnPACKer Dragon UnPACKer 5 Archive

It is an open source game archive (Quake PAK) unpacking program.