Ubex is a global decentralized advertising exchange, operating fully on the basis of neural networks with the use of blockchain and smart contracts. Ubex allows passage from the traditional pay per click scheme to the model of payment for targeted actions, the most fair and interesting model for advertisers. At the heart of Ubex’s advertising purchasing algorithms, lie neural networks that process information about each visitor to the member networks’ websites. The neural networks evaluate the interests of users, calculate the likelihood of targeted actions for all advertiser offers, and choose the most suitable advertisement. Thanks to this, member network website visitors see only those ads that are maximally confined to their interests, and which would convince them to fulfill the target action with maximum probability. Thus, Ubex maximizes the targeting of advertising and the economic efficiency for advertisers. Ubex aims to solve the problem of low confidence in the purchase of digital advertising. Smart contracts allow for making the relationship of advertisers and publishers (owners of ad slots on sites) as transparent and fair as possible, as well as minimizing the risks for all parties. By applying such an approach, Ubex allows passage from the traditional pay per click scheme to the model of payment for targeted actions, the most fair and interesting model for advertisers.