Methods, systems, and apparatus, including computer programs encoded on computer storage media, for blockchain-based notification are provided. One of the methods includes: obtaining, from a computing device associated with a first decentralized identifier (DID), a query about event data; in response to the obtained query, searching a data store to obtain one or more notifications for event data associated with a second DID, wherein a DID document associated with the second DID comprises the first DID, and wherein the DID document is stored in a blockchain; and providing the one or more notifications for the computing device associated with the first DID.