The awareness among people, companies and societies concerning environmental impacts has markedly increased in recent years. This has led many firms and practitioners to consider environmental aspects in various areas such as product development, service, and other areas. Product-based companies have realized that making environmentally sustainable products can be to their competitive advantage in the global market. To make sustainable products, companies need to integrate environmental issues into their product development processes. Accordingly, numerous eco-design tools have been developed. A majority of these tools can be applied only at later stages in the product development process to redesign products. However, the most effective way to consider environmental factors is to incorporate these issues at early stages in the process including planning and conceptual design phases. Therefore, this paper aims to identify applicable eco-design tools in the early stages of the product development process. In this paper, 77 eco-design tools were analyzed in-depth in accordance with their fundamental attributes and features, and then they were classified systematically. Based on this analysis, those applicable eco-design tools in the early stages of the product development process were identified and recommended accordingly. With regards to the findings of this research, only a limited number of eco-design tools can be used in the early integration of environmental impacts in the product development process. It is expected that this study will help eco-design practitioners choose proper eco-design tools for the early introduction of environmental issues and consequently, to design and develop environmentally sustainable products.