Can't recommend Filepicker enough. If your product involves any sort of document/photo access, you should try them out! I've been using it for a few months and have been pleased with the integration friendliness for a web-first developer like myself, the enthusiastic support (of course, small team, we'll how it scales), and variety of services connected. I especially like the "filter services by mime type" feature. The "save to" is massively useful from a consumer perspective as well.

Edit: A bit more context more my enthusiasm.