I'm using Sulvo to run my ads again, and they have an option to "add Prebid connectors to your auctions".
When I select one I have to enter data for it, so I'm guessing that I have to sign up for them each individually.
Here are the Prebid connectors offered. Are any of them worth the effort?
33 Across
Appnexus
Conversant Media
DistrictM
ETarget
Gourmet ads
IndexExchange
Lockerdome
Media.net
OpenX
Pubmatic
RTBHouse
Rubicon
Sovrn
Teads
TripleLift
Underdog media
Yahoo SSP
