There are a bunch of alternative CDNs, from what I found late last year there are basically zero other unmetered CDNs though - they all charge for transfer cost

There are a bunch of alternative CDNs, from what I found late last year there are basically zero other unmetered CDNs though - they all charge for transfer costs, so if your outbound traffic levels are high, it may be prohibitively expensive to change to an alternative CDN.