Individuals and businesses fund rural communities to plant and sustain traceable trees. These communities are mainly located in underdeveloped and developing countries. As the trees grow, they release Oxygen (O2), a secure token on Ethereum blockchain. The token represents a traceable carbon-credit. Treejer enables a decentralized voluntary market where carbon footprint can be reduced more transaprently. Moreover, it provides open data for scientists and economists who study the social and environmental impact of trees.