Oslo has municipal-owned public parking, as well as private parking spots.
Prices differ depending on the zone, time and particular place you are parking in.
Public parking in the city center is paid from Monday to Friday between 9am and 8pm. The parking is free after 8pm, as well as every Sunday.
Outside of the city center public parking is available as well, divided into zones, some of which are free of charge. Some zones have a time limit for parking i.e. you can only park for a particular period of time at once. In every parking zone there are signs that show parking rules at that particular spot.
You can download the Bil I Oslo app to pay fares for public parking. The app provides you with a confirmation that the fare has been paid for your particular parking spot. You can also pay parking on machines that accept Norwegian Crowns (coins), as well as Visa, American Express, and MasterCard/ Eurocard credit cards as payment methods.
You can see the map of parking zones on the link below:
http://www.arcgis.com/apps/webappviewer/index.html?id=8e6ab845c33342d1811259b0abc49a34&extent=593512.5204,6641105.451,601640.5367,6645010.7088,25832
Private parking includes garages as open parking.