Corruption is endemic in emerging economies – many transactions of private citizens with government institutions require the payment of bribes. While well known as a general phenomenon, specific data about the "bribe economy" is hard to come by. But such data is needed for rational responses to corruption at the societal and individual level – to expose it; to know which offices to avoid; or to know how much to pay if other recourse is not available. In response to a corruption survey of 102 participants, we have developed Bribecaster, a web application and an Android app to enable citizens to report and consume corruption information about dealing with government offices. Bribecaster uses a novel privacy-preserving implicit login schema and one-way hashing for protecting user identities while simultaneously ensuring the accuracy and integrity of reports. This citizen-induced transparency facilitates rational social and individual responses to corruption. Participants in a first-use user study rated Bribecaster highly for its usefulness.