CloudExplorer!

Uploadcare provides cloud storage, media uploading, image processing, and CDN for your website or app. Add media from your local storage, any URL, Facebook, Instagram, Dropbox, Google Drive, OneDrive, Evernote, and more. Upoadcare is highly optimized for adaptive web designs and reducing site loading times.

Filestack provides everything a developer needs when working with user content, from connecting to over 15 cloud storage services like Dropbox, Facebook, and Google Drive, to large file uploading directly to S3, to advanced conversion and post-processing functionality. All this in an world-class API with fantastic support

Kloudless is a developer tool that allows developers to work with any storage service through a single, unified API.

Cloud Explorer is a open-source S3 client. It works on Windows, Linux, and Mac. It has a graphical and command line interface for each supported operating system.

AssetPicker is a free asset or file picker designed to be easily included into web application interfaces. It has a file abstraction layer allowing adapters to connect to any remote storage, be it cloud storages like Amazon S3, Google Drive or Dropbox or assets from a custom web application server. In opposite to other file managers or pickers, AssetPicker is suitable for hierarchical as well as associative file storages.

Receive print jobs, photos, videos, graphics and other large files on your site. Just copy and paste some HTML to get an upload form that looks like your site. Setup email alerts, password protection and PayPal integration.