can you defrag an ssd and if so what software is safe?

I have the sandisk ssd, and heard you shouldnt defrag them is that the case?

There’s no need/benefit to defrag a flash-based or solid-state drive.

Tapeworm is correct SSD do not need defrag. If you are using Win 7 or MAC OS 10.6 or higher then your OS supports TRIM. TRIM is sort of like defrag for SSD. If you ahve an older OS like XP you will need to get a third party TRIM tool. for more info on TRIM just google SSD TRIM. 

defragging if a fast way to kill an SSD it also significantly reduces performances as it negates any performance maintanance that TRIM would have done.

A good article explaining TRIM:

do not defrag