Abstract: The great influence of Bitcoin has promoted the rapid development of blockchain-based digital currencies, especially the altcoins, since 2013. However, most altcoins share similar source codes, resulting in concerns about code innovations. In this paper, an empirical study on existing altcoins is carried out to offer a thorough understanding of various aspects associated with altcoin innovations. Firstly, we construct the dataset of altcoins, including source code repository, GitHub fork relation, and market capitalization (cap). Then, we analyze the altcoin innovations from the perspective of source code similarities. The results demonstrate that more than 85