Looking for logging into the Web Api site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Web Api site. After that you can login as usual with your login credentials.
https://stackoverflow.com/questions/26503455/asp-net-web-api-login-method
https://mbaas.nifcloud.com/doc/current/rest/user/userLogin.html
https://docs.microsoft.com/ja-jp/aspnet/web-api/overview/security/external-authentication-services
https://docs.microsoft.com/ja-jp/aspnet/web-api/overview/security/individual-accounts-in-web-api
https://qiita.com/piromaru/items/fb881f529dc7762d8da0
https://qiita.com/ochiochi/items/966b884eb17045dfb929
https://www.bokukoko.info/entry/2015/12/20/%E8%AA%8D%E8%A8%BC%E3%82%92%E5%90%AB%E3%82%80_API_%E9%96%8B%E7%99%BA%E3%81%A7%E6%A4%9C%E8%A8%8E%E3%81%99%E3%81%B9%E3%81%8D%E3%81%93%E3%81%A8
http://blog.virtual-tech.net/2014/01/web-api.html
https://doc.ec-cube.net/api_authorization
https://developer.mozilla.org/ja/docs/Web/API/Web_Authentication_API
http://jasonwatmore.com/post/2018/06/26/aspnet-core-21-simple-api-for-authentication-registration-and-user-management