Witnet

The Witnet protocol creates an overlay network that connects smart contracts to any online data source. Sport results, stock prices, weather forecasts, randomness sources or even other blockchains can be easily queried (preferably through APIs).

The protocol describes a distributed network of peer nodes— colloquially named witnesses- who earn Wit tokens as a reward for retrieving web data and reporting it directly to the smart contracts.

The bottom line is that a considerable number of randomly selected, anonymous peers retrieving information from one or more sources can converge into a single truth about the data they retrieved if they are incentivized to report the retrieved data honestly, they are punished or slashed for any wrongdoing, and they apply a common consensus algorithm that resolves inconsistencies.