We built an application on Shopify and it is in the final phase.It does not require any billing as it is free but as per rules of Shopify, we need to implement a billing API,
The least amount which is allowed is 0.5$ but I want to make it 0$.How it can be done?
Can you provide any guidance or provide a link to the docs where it is done?
But when I submitted the application for review, it got rejected because of mandatory billing API. This is the screenshot from one of the mails which I got from the team.
After looking into this further, it appears I was incorrect initially. My apologies. As of 2019 and going forward, it is a requirement for every app on the Shopify App store to use the Billing API in order to optimize the merchant experience and for tracking purposes (as mentioned in your provided screenshot).
As a workaround for your free app, you should be able to charge 0.00 if you use RecurringApplicationCharge as your resource for charging merchants. As per the documentation on Usage Charges:
A common billing scenario is to charge only usage-based fees, without a flat recurring monthly fee. To charge only usage-based fees, without a recurring monthly fee, first create a recurring application charge with a price of $0.00, and then apply the usage charge.