AppNexus and Index Exchange have expanded their header bidding partnership to include the support of server-to-server integrations.

This expansion will see both works as partners in each other’s server-side solutions – following on from their agreement to support each other’s header-based wrapper in May 2016.

Server-to-server integrations run a unified auction in which supply side platforms act as demand sources and bid on publisher’s inventory. This auction takes places in the technology provider’s servers rather than the publisher’s header.

“We strongly believe that publishers should have unbiased and transparent access to every exchange, not just the one that comes with their ad server,” said Tom Shields, CSO at AppNexus. “Our server-to-server offering builds on our years of delivering fast, reliable server-side connections to hundreds of industry partners, and just like the open source prebid.js, allows publishers transparent access to the exchanges that work best for them.”

Drew Bradstock, SVP of product at Index Exchange, added: “Successful server-to-server connections depend on strong infrastructure and transparent reporting practices. Our solution will allow for full transparency into auction dynamics so media companies can decide which partners perform best client-side or server-side and whether mediation is the best fit for them.”