ID-porten is the main login route in Altinn, and is a common solution for many public services.
ID-porten is operated by The Agency for Public Management and e-Government (Difi), and has its own user support.
You will find contact information and help with logging on at ID-porten.no
You will find ID-porten by clicking Log on to your top right or by clicking the picture below.
Note that the login method that you choose, will determine which safety level you are in. Some services require login with safety level 4, but in most cases safety level 3 will be sufficient.
Information about different security levels.