A method of non-interactive zero-knowledge crowd verifiable digital contact tracing, system and devices that provides improved accuracy and/or privacy by improving the validity of digital contact tracing sources. Private information associated with a respective user intended for a receiver is uploaded to a data server. The receiver is notified that the private information has been uploaded to the data server. A proof of the private information is generated using a proof function of a non-interactive zero-knowledge cryptographic protocol and added to a contact tracing blockchain for the respective user. A second blockchain transaction is added in response to verification of the proof by a verifier network using a verification function of the non-interactive zero-knowledge cryptographic protocol and the receiver is be notified.