While some of these courses are offered freely, you may be required to pay a minimal fee for issuing of certificate for some online courses.

1. National Open Learning Systems (click on Higher Education)

2. University of Johannesburg (UJ MOOCS)

2. Alison

3. Coursera: Coursera provides free courses from top universities and institutions. While some courses offer certificates for a fee, you can still audit many courses for free.

4. edX: Similar to Coursera, edX offers free online courses from prestigious universities, though you can also pay for certificates if desired

5. Khan Academy: Khan Academy is known for its extensive collection of free educational videos and exercises on various subjects, primarily focusing on basic education.

6. MIT OpenCourseWare: Massachusetts Institute of Technology (MIT) provides free access to course materials of their undergraduate and graduate-level classes.

7. Stanford Online: Stanford University offers a selection of free online courses across different disciplines.

8. Harvard Online Learning: Harvard University provides free online courses through HarvardX

9. Udemy: While Udemy is primarily a paid course platform, they also offer a selection of free courses on various topics.

10. FutureLearn: FutureLearn offers both free and paid courses from universities and institutions worldwide.

11. Codecademy: If you're interested in learning to code, Codecademy offers free interactive coding lessons.

12. YouTube: YouTube is a valuable resource for free educational content. Many educators and channels offer courses on a wide range of subjects.