  In centralized mechanisms and platforms, participants do not fully observe
each others' type reports. Hence, if there is a deviation from the promised
mechanism, participants may be unable to detect it. We formalize a notion of
auditabilty that captures how easy or hard it is to detect deviations from a
mechanism. We find a stark contrast between the auditabilities of prominent
mechanisms. We also provide tight characterizations of maximally auditable
classes of allocation mechanisms.
