The best open source alternative to Carambis Driver Updater is Driver Store Explorer, which is both free and Open Source. If that doesn't work for you, our users have ranked more than 25 alternatives to Carambis Driver Updater, but unfortunately only two of them is open source.
Driver Store Explorer helps you manage your Windows drivers. Enumerate, add and delete drivers with ease. FEATURES Enumerate / List all the packages staged in the local or offline driver store. Export the driver list as CSV.
DriverBackup is a lightweight driver-backup tool. The application is portable with a caveat: you'll need administrative privileges for full use. You can opt to backup one or all of your drivers, the backed up files are dumped into a tree structure based on driver name.