Standardization serves a as a means to improve overall quality of life through the economies of scale gained from the pervasive adoption of technical solutions. It enables competition by facilitating interoperability between products of different vendors. The wider open source community develops free and open source software (FOSS) in a global upstream/downstream model that similarly benefits society as a public good. FOSS and standards setting organizations (SSOs) are both instruments causing standardizing effects. Innovators and policy-makers assume that a mutually beneficial collaboration between them is desirable. However, their exact relationship is not fully understood, especially when and how FOSS and SSOs complement each other, or displace each other as competitors. To be able to compare FOSS and SSOs, our study develops a phase model of standardization that is applicable to both approaches, and applies this model to compare the strengths and weaknesses of FOSS and SSOs against common opportunities and threats in the ICT sector. Based on qualitative expert interviews with FOSS and SSO representatives, the synthesis of the separate results support conclusions from a product, a process and a societal perspective. The study identifies cost of change as a key determinant for the efficacy of each approach. It concludes that FOSS and SSOs create complementary products, compete for efficiency of the standardization process, and are both independent and complementary standardization instruments available to industry and influenceable by policy-makers. The paper closes with a discussion of possible implications relevant to businesses, the wider open source community, SSOs and policy-makers.