How to return 401 authentication from flask API?
This is a common problem when working with REST APIs and browser clients. Unfortunately there is no clean way to prevent the browser from displaying the popup. But there are tricks that you can do:

You can return a non-401 status code. For example, return 403. Technically it is wrong, but if you have control of the client-side API, you can make it work. The browser will only display the login dialog when it gets a 401.
Another maybe a bit cleaner trick is to leave the 401 in the response, but not include the WWW-Authenticate header in your response. This will also stop the login dialog from appearing.
And yet another (that I haven't tried myself, but have seen mentioned elsewhere) is to leave the 401 and the WWW-Authenticate, but change the auth method from Basic to something else that is unknown to the browser (i.e. not Basic and not Digest). For example, make it CustomBasic.
I have developed an API in flask which is using HttpBasicAuth to authenticate users. API is working absolutely fine in fiddler and returning 401 when we pass wrong credential but when I am using the same on login page I am getting extra pop up from browser. I really don't want to see this extra pop-up which is asking for credential (default behaviour of browser when returning 

401

with 

WWW-Authenticate: Basic realm="Authentication Required"

).
It is working fine when deployed locally but not working when hosted on remote server. 
How can we implement 401 which will not let browser to display popup asking for credentials.