DODO, the Directory of Online Dual-enrollment Options, helps high school students and their families compare online dual-enrollment, dual-credit, and early-college courses. Its directory lists more than 7,000 courses from over 90 regionally accredited U.S. colleges and universities, with options for public-school, private-school, and homeschooled students. Courses are available online and range from introductory college level through advanced undergraduate subjects; the site reports that more than 7,000 courses are available to U.S. residents and over 4,000 to students worldwide.

DODO provides course and program details, including tuition, schedules, admissions policies, and recent course offerings. Search and sorting tools, quick-compare charts, filters, course lists, and school shortlists help users find options suited to their budget, schedule, age, high-school year, GPA, and test scores. The directory spans core academic subjects and specialized interests, with examples including calculus, business law, astronomy, animation, and machine learning. Visitors can view the course list for free; access to college names and detailed pricing, schedule, and admissions information is offered through an annual subscription listed at $29.99 USD.