The West African Examinations Council, set up in 1952 and shared by Ghana, Nigeria, Sierra Leone, The Gambia and Liberia.
It sets and marks the BECE and the WASSCE, issues the certificates, and runs the results checkers that every Ghanaian household refreshes on the day.
Two practical things. WAEC publishes the syllabus for each subject, and it is free - which makes it a better guide to what will be examined than any revision book written about it. And WAEC is the body that verifies a certificate for a foreign university or employer, which is a service you apply and pay for rather than something a school can do.