Defraggler is a free disk defragmenting tool that can analyze and defragment selected hard drives or even individual folders. Periodically, defragmentation is essential to keep drives in good shape and to allocate disk space more effeciently.
Download it from here.
Using it is pretty simple, just launch it and all the existing drives (both internal and external) will be displayed along with useful stats like drive temperature, health, read/write stats and so on.
The defragmentation can be either the thorough type which will take a while to complete or a quick one. Either right click on specific drive and select that or access the same from Action > Defrag.
Apart from this, scheduled defragmentation can be configured for specific drives. Access the same using Settings > Schedule.
Just like drives, simply right click on any folder that needs to be defragmented and select Defraggler > Defragment.
The tool is low on resource consumption and pretty simple to use.