The classic file store. S3 stands for Simple Storage Service. Files are stored in "buckets" and you can configure permissions and policies for access and behavior.
Azure Blob storage is Microsoft's object storage solution for the cloud. Blob storage is optimized for storing massive amounts of unstructured data.
Cloudinary does fancy image/video stuff like manipulation and optimization, but will also directly host for you, making it a good fit for serverless projects.
Filebase provides S3-compatible object storage at a fraction of the price and it is backed by blockchain technology.
Firebase Cloud Storage is built for app developers who need to store and serve user-generated content, such as photos or videos.
Goobox is a zero-knowledge, end-to-end encrypted file sharing service that utilizes decentralized cloud network Sia for its storage layer. It offers S3-compatible APIs to interact with the storage.
ZeroBit allows developers to easily store content on a secure and permenant cloud with an API.