Is "adding .json to the page URL" still supported?

This feature still works when the first time I install the manager.io but after I upgrade within in this December 2019, the “adding .json to the page URL” not works again (of course the latest version).
So, my question how can we get the json structure in the latest version?

Thank you.

Bump!
No anyone can give me an answer?

I suggest you provide more information about your question. Your initial post was not clear.

Thanks for your respond
The first time we use the manager.io from May 2019 (desktop version) then we built a server too and we bought a license on October 2019.
We use manager.io as our accounting system and pull/push data via JSON structure into our other system by add .json to the page URL like http://localhost:55555/customers.json?FileID=44a5451c-cb31-4dce-82c9-7e5149c58bae
(add .json after customer)
But after we upgrade our manager.io into version 19.11.75 and above/latest, we cannot got the JSON structure again by adding .json to the page URL from desktop or server version. Unfortunately manager.io not support downgrade version.
So, what should we do to get the JSON structure?
We have try other alternative by add API in URL page like http://localhost:55555/api/ but unfortunately we have to pull one by one data, not like by add .json in URL page

@cishpix the API for Manager is not fully implemented and it is only in the development stage as there is no official documentation or guide for it. so until it is implemented there is no guarantee that it will continue working the same way it used to work in older versions.

OMG, it’s really a frustation for our team because our application cannot pull data via JSON from manager.io
If can predict, how long we have to wait it?