The Box API supports two distinct methods of file upload. The supports files up to 50MB in size and sends all the binary
data to the Box API in 1 API request.
The support files from 20MB in size and allow an
application to upload the file in parts, allowing for more control to catch any
errors and retry parts individually.
To upload files to the Archive folder, you need to first enable the (GCM) scope in the Developer Console.
Upload limits
Upload limits are dictated by the type of account of the authenticated user.
More information can be found in our community article on this topic.
Preflight check
The Pre-flight check API allows an application to verify that a file will be
accepted by Box before it uploads any bytes. It can both be used for new files,
as well as uploading new versions of existing files.
Learn more about pre-flight checks
Upload domain
Uploads to Box happen via a different domain (upload.box.com) than regular API
calls. This is something to keep in mind when writing your own upload code. All
the Box SDKs will take care of choosing the right domain for the right API call. 
