post https://broker-api.sandbox.alpaca.markets/v1/accounts//documents/upload
Upload documents for the primary account owner of an account.
Documents are binary objects whose contents are encoded in base64. Each encoded content size is limited to 10MB if you use Alpaca for KYCaaS. If you perform your own KYC there are no document size limitations.
As a convenience, documents of type w8ben may be uploaded as a JSON object using the content_data request property. The Alpaca system will then generate a formatted W-8 BEN document for subsequent downloads.
Note that these owner documents are distinct from the account documents generated by Alpaca, such as tax statements and trade confirmations.