Yes, Onsego30 is legit. Onsego30 is a part of the Onsego GED Prep System. Onsego is accredited by GED Testing Service.
The GED test is provided by the GED Testing Service, and students schedule their tests at GED.com.
GED.com includes Onsego, together with 19 other certified publishers, on the list of trusted prep programs that meet the GED test objectives and have a high level of instructional integrity.
