It exists dear! With Shopify's Digital Downloads app, you can upload digital files like videos, songs, and graphic art as products in your store. When a customer purchases the digital product, they receive a link to download the file.
The three main sections in the Digital Downloads app are:
I found this content in the user manual of apps by Shopify. >>https://help.shopify.com/en/manual/apps/apps-by-shopify/digital-downloads
Also, an app called SendOwl would help in selling digital files and downloads. It provides instant and automatic delivery and proven performance.
None of this information answers the question. I'm also looking for a way to automate adding digital downloads through an API. The Digital Downloads app does not provide one, and while SendOwl does have an API it doesn't seem to have the features needed to add a download to an existing Shopify Product.
Finally I managed it.
I am using sendOWL. Then, I have created a Lambda function in Amazon that gives me back the URL of sendOWL from a title that provides and some customer information to validate the request (I use email, Id and createdAt fields to verify the access).
If anyone wants more details, just let me know it or write me an email to firstname.lastname@example.org