I have been using Yellow Circle as a completely free (and no CC required) alternative to the 'free' Cloud accounts through the major vendors. Unfortunately it seems they have recently changed things so that even the lowest account has a $1 cost now... While admittedly quite reasonable for what they do, it takes away a free educational resource for teaching / demoing Cloud which I'm sad to see go. Also, even these prices might not last based on the 'limited time only' wording.
Student Sign Up – Yellow Circle Learning Platform
yellowcircle.net