When the say the best things in life are free, you can safely say they have Udacity in mind. Udacity offers courses developed by the world's leading companies and experts. And their certificate courses don't come cheap at all. As much as I love learning and won't hesitate to spend to learn every time I come to check the amazing courses Udacity have and feel tempted to enroll, the moment I see the fees the temptation and I both disappear. But the good part is that they've got many great courses they've made available for free.
I have not wasted time in registering for the ones I have interest in, and I suggest you go check out and enroll for the ones you find of value too at www.udacity.com
Check out the catalog (see screenshots below)