We’re a fan — Filepicker.io
One of our web apps relies upon over a dozen third-party api-based services, and none are more impressive than Filepicker.io, a service that gracefully handles the gnarly details of providing a user-friendly, sexy, full-featured UI for customers to upload images.
Integrating Filepicker.io into our web app was a snap, due to their well-thought-out API and support for features such as upload-to-S3.
Their pricing has gone up quite a bit since the service was introduced in late 2013, but unlike some companies mentioned in this blog (yeah, I’m calling you out yet again, Zerigo) they grandfathered early adopters with a special plan.