A baby hammock is safe if you keep these points in mind: 

• Stay with your baby when the baby hammock.
• Hang the hammock up to 10 cm above the floor / bottom of the box.
• Put a mattress / pillow under the hammock   

A baby hammock from hangmatje.nl is safe and your baby will not fall out of the baby hammock. 

The baby lies in a natural position, curled, and is well supported. Babies often find it very comfortable to lie in a hammock.
Try the hammock, however, only when the baby is quiet and happy.