Looking for logging into the Ap1 Salesforce 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 Ap1 Salesforce site. After that you can login as usual with your login credentials.
https://login.salesforce.com/
https://developer.salesforce.com/forums/?id=906F00000008r5sIAA
https://success.salesforce.com/answers?id=90630000000gugYAAQ
https://books.google.com.pk/books?id=_-BPBAAAQBAJ&pg=PA121&lpg=PA121&dq=ap1+salesforce+login
https://workbench.developerforce.com/
https://community.zuora.com/t5/Partner-Announcements/Salesforce-Salesforce-AP1-Maintenance-Information/ba-p/18071
https://salesforce.stackexchange.com/questions/49861/is-there-a-way-to-customize-partner-portal-login-url
https://docs.servicerocket.com/salesforce-confluence-server/administrator-guide/configuring-the-connector
https://community.tibco.com/questions/issue-integration-business-works-salesforcecom
https://stackoverflow.com/questions/40863425/perl-rest-integration-with-salesforce-report?rq=1
https://stackoverflow.com/questions/24817738/open-particular-salesforce-lead-id-in-browser-from-net-project-using-server-url
https://stackoverflow.com/questions/14998524/salesforce-how-to-login-with-javascript-without-security-token
http://websites.milonic.com/ap1.salesforce.com