Storage in European cities is generally very expansive (e.g. in Paris : 50€ /m2 = 6$ / square foot) and quite far from home.
Costockage helps people looking for storage space, such as students, or families moving appartment, to find a close to home and 30 to 50% cheaper alternative to self storage in Europe. Insurance included.
At the same time, it helps the owner of extra room inside or outside his home to list a space for free in 3 minutes. He will be able to make around 150€ (200$) a month with renting a standard room.