Looking for logging into the Sage Notebook 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 Sage Notebook site. After that you can login as usual with your login credentials.
https://ask.sagemath.org/question/9694/how-do-i-sign-in-to-my-sage-localhost-notebook/
https://trac.sagemath.org/login
https://sage.hs-mittweida.de/
http://sage.math.canterbury.ac.nz/
https://sage.icse.us.edu.pl/
https://cocalc.com/
https://en.wikipedia.org/wiki/SageMath
https://github.com/sagemath/sagenb
https://github.com/sagemath/docker-images
https://groups.google.com/d/topic/sage-support/1LwEkU7F3G8
https://wiki.archlinux.org/index.php/SageMath
https://itunes.apple.com/de/app/sage-math/id496492945?mt=8
https://sagemath.kangwon.ac.kr:8431/