The card sort technique has many uses in HCI research and practice. Card sorts have traditionally been conducted with physical cards but now programs are available for this task. It is unclear if results from an online version of this technique are as reliable as the “oncard” version. This paper presents a study comparing oncard and online versions of the card sort technique for card set reflecting the information architecture (IA) of two website domains (museum and news sites). No differences were found between the two versions. However, the online version took significantly longer for participants than the oncard version, particularly for non-native English speakers. The card sort technique was also able to reveal cultural differences between mental models of British, Chinese and Indian participants of the IAs of both museum and news websites and showed that all participants have mental models that differ substantially from the typical IAs of websites in these domains.