I don't want to create a schema in a relational database for that kind of use case. A MongoDB fits as well.
Edit: Sorry for my short and unprecise comment. I regret posting it, loosing all my Karma. Yes, of course I would use a schema, but I may use hundreds to get my products presented with all attributes and variants available. There is a set of attributes that will remain for all products, others will vary, some will change and will be dropped. Some may be conditional, depending on size or color. I could model that in RDBMS as well, adding those properties in an additional JSON or something else.
Yes, I'm also mainly using relational databases and just wanted to give an example of a use-case for MongoDB. I regret, sorry.