SaaS3 is the next-generation SaaS for fully decentralized applications. It is based on a decentralized, permissionless oracle network that enables off-chain data feeds of any data category to be uploaded to the on-chain. It also provides trustworthy off-chain computation services, eliminating the need for centralized servers as SaaS3 miners provide computation resources. Developers can easily configure their own oracles and deploy any web2 API.