Open Source development could be analyzed based on a number of key factors; ranging from developer roles to investigating the community around a project, the target audience and the programming platform support for an open source project. Interestingly, open source development is usually described with onion structure. Paradigm examples are Crowston’s Onion as discussed in Crowston and Howison (2003); Kumiyo’s Onion as found in Kumiyo, Yasuhiro et al. (2002)); Antikainen’s Linux Onion (Antikainen, Aaltonen et al. 2007) and Herraiz’s Onion (Herraiz, Gregorio et al. 2006). The Open Onion research has evolved a robust open onion model of open source development by merging the onion layers within the four earlier mentioned open source onions. With this approach, a unique open onion model has evolved from the consolidated un-validated earlier onion models of open source. The novelty of this research lies in the validation of the layers within the open onion model. This paper only provides a detailed assessment of the developer layer of the open onion. Table 1 shows the evolution of the open onion model and developer layer is prominent within the onion model of open source.