London - Openads, a developer of free, open source ad server software, announced on Wednesday that it has raised $15.5 million in its second round of financing, led by Accel Partners.

If the future of advertising is online, many companies, including Google, Yahoo, Microsoft, and WPP, are betting that the future of online advertising is in ad networks, i.e. centralized platforms for the buying and selling ads, where the company that controls the network controls the sale and the flow of revenue to the publisher. This is entirely counter to traditional ad sales model, where the publisher controlled the sales channel — unfortunately, there weren’t (and still aren’t) many metrics or ROI involved, which has lead to the rise of online ad networks, with Google’s AdSense leading the way. But is it possible that online publishers, perhaps from the bottom up, might start to wrestle control away from the ad networks?

London - Openads, the developer of a free, open-source ad server for online publishers, announced on Wednesday that it has raised $5 million in its first round of financing, led by Index Ventures.