Shopping cart framework that supports multiple vendors?
I'm searching for a shopping cart or web store framework that **supports multiple vendors**.

There are [many, many shopping cart frameworks out there][1]: that page lists couple of hundred.  In spite of the comparisons on that page, supporting multiple vendors isn't a comparison item, probably because it's a rare requirement.  Separate to that page I have evaluated a few of what appear to be the top frameworks, and none that I evaluated supported this feature.  Which carts would you recommend?

 - Commercial is okay, although I would prefer open source.
 - Platform (Windows, Linux, ASP.Net, PHP, Ruby... Minix, Fortran... :)) doesn't matter.
 - A system
   where I manually add vendors who request it (instead of them freely
   being able to sign up) is also okay, if there's a store where that's
   possible but freely joining up isn't built in yet.

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**Rationale:** I'd like to create an app-store like website.  "App store" is a close analogy: it won't sell apps, but it will sell digital goods and I'd like anyone to be able to sell their item on the store.  It's this second requirement, multiple vendors selling through the store, that I'm finding hard to satisfy.


  [1]: http://en.wikipedia.org/wiki/Comparison_of_shopping_cart_software
Shopping cart framework that supports multiple vendors?
===

I'm searching for a shopping cart or web store framework that **supports multiple vendors**.

There are [many, many shopping cart frameworks out there][1]: that page lists couple of hundred.  In spite of the comparisons on that page, supporting multiple vendors isn't a comparison item, probably because it's a rare requirement.  Separate to that page I have evaluated a few of what appear to be the top frameworks, and none that I evaluated supported this feature.  Which carts would you recommend?

 - Commercial is okay, although I would prefer open source.
 - Platform (Windows, Linux, ASP.Net, PHP, Ruby... Minix, Fortran... :)) doesn't matter.
 - A system
   where I manually add vendors who request it (instead of them freely
   being able to sign up) is also okay, if there's a store where that's
   possible but freely joining up isn't built in yet.

----------

**Rationale:** I'd like to create an app-store like website.  "App store" is a close analogy: it won't sell apps, but it will sell digital goods and I'd like anyone to be able to sell their item on the store.  It's this second requirement, multiple vendors selling through the store, that I'm finding hard to satisfy.


  [1]: http://en.wikipedia.org/wiki/Comparison_of_shopping_cart_software