The short version of the answer for those of you in a hurry, would be Kiwi or Rema1000.
For the rest of you who are a little bit more curious, here's a more detailed version.
Kiwi and Rema1000 are the two most widespread players. There are other contenders but the market is pretty much "monopolized" by these two, Rema1000 being the bigger fish in the pond. You can't miss them, they pop up all over the city like mushrooms. Prices vary, I mean maybe eggs are cheaper in one but apples in the other but it averages out so it is a matter of preference and location availability. To name a few other chains, there is Rimi, Bunnpris, Europris, Coop, Spar, Global Food.
As you'll see below these chains happen to be owned by the same bigger fish, just pimped under a different label.
The Kiwi chain owned by NorgesGruppen, has a low cost item brand "FirstPrice". Not to be disregarded. Study and test show that cheap doesn't always mean bad quality. It was owned by the late Mr. Per-Erik Burud, who bought himself in the business, back in 1991 when the chain only had 8 stores. Now it is driven by a joint venture between Norges Gruppen and Dagrofa. Dagrofa being a Danish retail company that controls distribution to other franchise stores like Spar, Meny. As a side note, in 2013, NorgesGruppen bought a 49% share in Dagrofa from Skandinavisk Holding (owner of Scandinavian Tobacco Group, acquired by British American Tobacco). It is interesting to see where the chains lead 🙂 isn't it?! Those interested can do further research on their own. We'll get back on topic.
Rema1000 is a multinational supermarket chain, owned by Reitangruppen. In 2008, they under the Rema1000 name bought all operations of Lidl in Norway. The group also entered into a collaboration with Shell in Scandinavia re-profiling of a total of 269 service stations. The service stations were re-profiled to Shell stations. The attached convenience stores to 7-Eleven-s. They also have their hands in other pots like Narvesen. A Norwegian chain of convenience stores/news agents. Real estate and so on.
Rema, is short for Reitan Mat ("mat", meaning food), referring to Odd Reitan, you guessed it, the founder of the company (1979). Their slogan being "The simple is often the best” (“Det enkle er ofte det beste”). We usually shop here out of habit I'd say but Kiwi is just as good. 1000 stands for the more than 1000 different products they offer.
Bunnpris, yet another Norwegian retail chain.
Coop, owned by the Norwegian Cooperative Association, that acquired margarine factories, cigarette factories and coffee plants just to name a few, before re-branding themselves to Coop in 2000. They also have a real estate business.
Spar, the Dutch multinational retail chain.
Lerøy, For fresh seafood products.
There are also several minority owned smaller businesses / grocery stores, that import and sell, in this part or the world considered exotic foods and ingredients, like for example Global Food (CEO - Abbas Hezari). Example would be spices, Sauerkraut and so on.
So, to recap, Rema1000, Kiwi, Bunnpris, Rimi, Coop, Spar, Global Food for grocery shopping.
You'll also find Burger King and McDonald's here and there but I've left these last for a reason ;). I'd say Burger King-s are cleaner. No Colonel Sanders unfortunately. 🙁
So that is about it. Those are your options. As a tourist or newcomer looking for the lowest prices you can't go wrong with Rema1000 or Kiwi or any of the other grocery stores given that you find those in the area you are in. Try to avoid shopping at fuel stations or bus/train stations if you don't want to pay extra. A short walk pretty much anywhere in the city and you are bound to find one of the above mentioned chains and save some money.
As for alcoholic beverages... we now arrived in "deep-pocket" land 🙂
Vinmonopolet (founded in 1922), is the place you seek if you want anything other than beer (they also got a wider range of beer also compared to what one can find in a regular grocery store). In them' grocery stores boil down your expectations to beer (and sometimes wine). Other fun fact. In the latter you can only purchase beer until 8 pm during the week and 6 pm in the weekends so you'd better think ahead if you plan on drinking. Vinmonopolet outlets close at about 6 pm if memory serves well.
Don't smoke or poison myself with snus (moist powder tobacco that people jam under their upper lip to get dizzy and look like they've been in a fight not so long ago) so I have no idea if there's any sort of restrictions on smokable / nicotine containing items. As I said. Smoking and drinking is expensive in these parts but back to drinking. You can only buy beer at grocery stores until 8pm during weekdays and until 6pm on the weekends. Weekends meaning Saturdays, because on Sundays 99.9% of all stores are closed (one exception being Bunnpris). I just repeat myself so it sinks in :).
Vinmonopolet, is a government-owned alcoholic beverage retailer. It is the ONLY company allowed to sell beverages containing an alcohol content higher than 4.75% in Norway. People in, I think it is safe to generalize, Scandinavian lands like to drink. A lot.
So the government monopolized the alcohol industry with the average Martin / Silje (these being the most common names in Norway so they claim) in mind. The government being your friend and all feels socially responsible for your health, so it holds your hand and limits citizens' consumption of alcohol, because it cares... and has no other choice but to, monopolize selling, offer limited access and last but not least introduce high costs (cough-profit-cough), for your own good :). On the flip side this way they also prevent selling alcohol to minors and drunk would-be customers. You'll get used to it. I for one being a casual drinker, don't mind, but it is obvious that this is not about Martin's well-being, but how should I put this, other interests. Talking about interests, since August 2006, after a huge corruption case Kai Henning Gjesdal Henriksen, became the "top-pimp" running the company. Whom' happens to be a former politician of the Conservative Party of Norway, slash business man 🙂 ...
Anyways, I'm sure I've made you curious so if you visit this page of the official Vinmonopolet website you can browse products and prices. They got quite a range of products.
Hope you found this info useful.
Until next time, "have it good".