There are two File services:
The Global Files service (called the S3 Service in our docs,) is for files that are manually uploaded via the web-portal. Those files are intended to be downloaded by all/any of your users. Those files max out at 50MB. There is no hard limit as to how many of them you can have - but commonly apps don't have more than a few dozen (and those files are mostly used for configuration, media, and assets).
The User Files service (called the File Service in our docs,) is for files associated with Users. They can be uploaded by the client to the system, and are owned/associated with the user that uploaded the file. User Files are restricted to 20MB each. There isn't a hard limit on how many you can have.
Depending upon your plan, there is an overall file storage maximum - the Standard Plan is 1GB, the Business Plan is 2GB. You are charged $0.05 / GB for extra storage.
You are also charged for uploads/downloads of files. In the Standard Plan, the first 10GB (per month) is free - in the Business Plan, it's the first 20GB (per month). For any additional after that, there is $0.15 per GB charge.
For more information on plan pricing, go to the Pricing Overview page. Click on the [Learn More] links to get more details on usage examples and overage charges.
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