Our main backend login can be accessed via https://webred.visma.x/siteui (where x represents the top level domain if your choice, like no/se/etc).
Our test server (for testing of new features before release etc) is found at https://test2webred.visma.x/siteui. The frontend should be accessed at https://test.visma.x.
Note that you need to be connected to a Visma network to be able to access the backend, either at a Visma location or via VPN/Citrix.
Read more about logging in at the official User Guide.