Commercial 360° photo viewer with a free plan for personal use. And you don't have to register to try it. You would have to register only if you need it for commercial use or want to manage your photos and customize viewers. Please note that the plan also defines your bandwidth limit, so make sure you choose one appropriate for your needs. Integration is done with an iframe.
Supported projections: equirectangular
Distribution Method: Cloud Service
Price: from $15/month with unlimited uploads