A system and computer-implemented method are provided for predicting user trustworthiness through location-based verification with social networking, and for providing an on-line platform for communicating trustworthiness information between different users. The system collects user time and location data to verify the trustworthiness of user transactions. Trustworthiness ratings are established in part by tracking, for particular transactions, time-varying geographic locations of one or more remote computing devices of one or more users associated with the particular transactions, and comparing the time-location data for the particular transactions with one or more time-based attributes or location-based attributes of the transactions.