The AdForecaster is the next-generation forecasting engine for online advertising campaigns. It overcomes various important limitations of existing forecast engines in ad servers, allowing an accurate prediction future ad impressions traffic levels and campaign inventory availability using an unlimited number of targeting variables, including geo, keywords, key-values, cookies and multiple frequency capping groups at banner, booking, line item or campaign level. It is operated as a Software-as-a-service, minimising integration and deployment times as well as operational maintenance costs. Custom-built Ad Servers and Exchanges, Sell-side platforms (SSPs) and Demand-side platforms (DSPs) are the most common type of platforms taking advantage of the AdForecaster.