Looking for logging into the Phpbb 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 Phpbb Api site. After that you can login as usual with your login credentials.
https://area51.phpbb.com/docs/dev/3.2.x/extensions/tutorial_authentication.html
https://wiki.phpbb.com/Authentication_plugins
https://www.phpbb.com/community/viewtopic.php?t=2367726
https://wiki.phpbb.com/Proposed_REST_API
https://www.phpbb.de/community/viewtopic.php?t=234948
https://docs.oneall.com/plugins/guide/social-login-phpbb/3.1/
https://stackoverflow.com/questions/45488720/phpbb-3-1-authentication-plugin
https://developer-blog.net/phpbb-automatischer-login-auf-externer-seite/
https://github.com/naderman/crowd-phpbb-auth
https://forums.eveonline.com/t/phpbb-3-2-eve-sso-esi-extension-beta/17046
http://www.lapk.org/board/docs/auth_api.html
https://www.abakus-internet-marketing.de/foren/viewtopic/t-138108.html
https://us.battle.net/forums/en/bnet/topic/14728823355