BTW, if you want to audit, you need to search for each course individually (or click seycombi's links above) and click the Enroll button there, there's no Audit option if you click Enroll on the full Specialization.

Thank you for pointing this out! Was looking for the way to just audit it and could not figure it out.

fast.ai also has a quality ML course

I love fast.ai's course, but I also appreciate having a solid and thorough free machine learning course. While fast.ai is good for getting onto the cutting edge of deep learning quickly, it doesn't go through a lot of material that most people in the machine learning industry are assumes to know.

Can the certificate be received by completing the course in audit mode and then paying at the end of the course.

Thanks for the links! It seems like you can already browse the lecture videos of the first three courses!