Amazon Simple Storage Service (Amazon S3), provides developers and IT teams with secure, durable, highly-scalable object storage. Amazon S3 is easy to use, with a simple web services interface to store and retrieve any amount of data from anywhere on the web. With Amazon S3, you pay only for the storage you actually use. There is no minimum fee and no setup cost.
Microsoft Azure Blob storage is a cloud computing PaaS that stores unstructured data in the cloud as objects/blobs. Blob storage can store any type of text or binary data, including documents, media files, and application installers.