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| Cicero Dental AS | Trondheim | 2023 |
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| Cidercompagniet AS | Odda | 2018 |
| Cignus Instruments AS | Oslo | 2020 |
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| Cimon Medical AS | Trondheim | 2019 |
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| Cinjat AS | Kautokeino | 2025 |
| Cipax Norge AS | Bjørkelangen | 2021 |
| Circadian Eyewear AS | Bergen | 2017 |
| Circmar AS | Oslo | 2020 |
| Circmet AS | Oslo | 2017 |
| Circularis AS | Ålesund | 2017 |
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| CL Service AS | Treungen | 2024 |
| CL3 Norge AS | Tvedestrand | 2022 |
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| Climbing Systems and Technology Ltd | Sl-8000 Novo Mesto | 2016 |
| CLM Rope Access Ltd | Arisaig Ph39 4Nw Scotland | 2018 |
| Cloud Surfers AS | Jar | 2023 |
| Cloudalarm AS | Gjerdrum | 2017 |
| Clover Tool Europe Limited | Portlethen Ab12 4Yf | 2019 |
| Clyde Union Limited | G74 5Pa East Kilbridge | 2009 |
| CM Biomass Partners | Dk-2100 København Ø | 2024 |
| CMD Holding AS | Oslo | 2019 |
| CMD Produksjon AS | Oslo | 2019 |
| CMK AS | Klepp Stasjon | 2016 |
| CMP Raufoss AS | Raufoss | 2014 |
| CNC Consult AS | Hommersåk | 2019 |
| CNC Dental AS | Kongsvinger | 2017 |
| CNC Kjeller'N AS | Gjøvik | 2026 |
| CNC Produksjon AS | Oslo | 2020 |
| CNC Produkter AS | Leksvik | 2023 |
| CNC Service AS | Oslo | 2013 |
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| Cnc-Holding AS | Leksvik | 2023 |
| Cnc-Protek AS | Moss | 2018 |
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| Coast Consult AS | Bergen | 2008 |
| Coatx AS | Sandefjord | 2022 |
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| Cobra Tech Norway AS | Langhus | 1991 |
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| Cockerel Games AS | Mosjøen | 2023 |
| Coco Kanel AS | Stavanger | 2023 |
| Cody AS | Skien | 2011 |
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| Colocem AS | Dalen | 2019 |
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| Colourkub Norge AS | Kongsvinger | 2017 |
| Colubris Water Solutions B.V. | 7102Dz Winterswijk | 2022 |
| Coma Design Da | Ålesund | 1999 |
| Combi Engineering Spolka Z Ograniczona Odpowiedzialnoscia Nuf | 47-223 Kedzierzyn-Kozle | 2024 |
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| Comlight AS | Skjeberg | 2007 |
| Como Mexico AS | Stavanger | 2017 |
| Compact Door Scandinavia AS | Fredrikstad | 2002 |
| Compact Food Solutions AS | Søfteland | 1990 |
| Complex Shipbuilding Services AS | Fitjar | 2022 |
| Complex Shipbuilding Services AS | Fitjar | 2026 |
| Complex Wind Service SRL Nuf | Ro-900619 Jud.Constanta | 2024 |
| Composit Holding AS | Nesbru | 2015 |
| Compositech AS | Lierskogen | 1996 |
| Compower AS | Blomsterdalen | 2021 |
| Compower Holding AS | Blomsterdalen | 2021 |
| Comrod AS | Tau | 1983 |
| Comrod Communication AS | Tau | 2006 |
| Comtron AS | Oslo | 2003 |