Announcement:I'm giving an API documentation workshop in Mountain View, California on August 30, 2019. If you're interested, you can register on EventBrite.
STC's Online Certificate Courses
First time I've seen STC Online Certificate Courses. They look excellent. $595 per course, and there are four courses, each consisting of 5-8 sessions per course. Each of the instructors looks solid. Thanks @AndreaJWenger for the link.