Thank you for you reply, Daniula.

I think that these two sites can not be compared.

Aldonio.com offers you, the seller, not only a place where you can sell your homemade code, but the seller/programmer also is able to blog about the product(s) he is selling and this information will be delivered to the mailinglist and the social media channels.

You can also make and edit your own product information. Payments are done by Paypal which is a reliabel partner. Sellboxhq.com is a bit confusing to me. I would like to see what they sell. But all I can find is a link to my own dropbox. Would you give a stranger entrance to your dropbox without knowing their intentions?