The TestDaF-Institut is an institute for language testing in Bochum, Germany. It runs the TestDaF, short for Test Deutsch als Fremdsprache: "Test of German as a foreign language", and is aimed at people who would like to study at German universities, academics and scientists.

The institute is part of the Society for Academic Study Preparation and Test Development, Gesellschaft für Akademische Studienvorbereitung und Testentwicklung e. V., based in Bonn, which was founded in 2000 by various German-language institutions including DAAD (German Academic Exchange Service), the Goethe-Institut, the distance learning university in Hagen, and the Carl Duisberg Centre in Cologne. The idea for the society came from the DAAD and the German Rectors' Conference (Hochschulrektorenkonferenz, HRK).

The test can be taken in 91 different countries around the world. The test covers listening comprehension, reading comprehension, writing and speaking, and is recognised by German universities as proof of prospective students' ability.

There are three levels (TDN 3–5) which correspond to the Common European Framework of Reference for Languages levels B2–C2.