Web3 startup Spindl has announced the launch of an on-chain advertising network. Founded by Silicon Valley veteran Antonio Garcia Martinez, the company connects advertisers, publishers, and so-called attribution providers that track the origins of customers. In this case, "publishers" are providers of crypto wallets, which increasingly resemble social applications with news feeds and "discover" tabs. The delivery of advertising content will still take place off-chain, but advertisers will transfer funds for advertising campaigns to smart contracts, which will only release funds to publishers after the attribution provider verifies that the advertisement has led to sales by reviewing on-chain data. (Coindesk)