Quizlet

Quizlet is a study platform built around flashcards, letting users create their own study sets or use sets made by others, then review material through modes such as practice tests, matching games and written recall exercises. It is used by students at various levels as well as teachers building study material for classes across many subjects and languages.

Its ads.txt file lists 61 ad systems, made up of 37 direct relationships and 45 resellers. Sales houses named include Next Millennium Media, EX.CO, Monet Engine and 33Across, reflecting a mix of direct and programmatic advertising on the site.