1. A method comprising, by one or more computing devices: sending, to a client system of a first user, instructions configured to present a translation prompt comprising a first text string; receiving, from the client system, a first input by the first user, wherein the first input corresponds to a first translation for the first text string; and calculating, by one or more of the computing devices, a reliability-value for the first translation based on the first input and a credibility-score of the first user, wherein the credibility-score of the first user is based on responses by the first user to checker-translation prompts, wherein the checker-translation prompts each comprise a control string for which a correct translation is known, and wherein the credibility-score is based on a number of responses by the first user that match the respective correct translations for the control strings.