Initial Coin Offerings (ICOs) are an emerging form of crowdfunding for blockchain-based startups. While ICO design varies greatly in practice, many service-based platforms (e.g., Ethereum), use "uncapped" structures that forego limits on token supply, subjecting early investors to dilution risk. In this paper, we examine the conditions under which such ICOs are optimal and provide guidance for their design. Despite their popularity in practice, uncapped ICOs are understudied and not as well understood as their capped counterparts. We model game-theoretic interactions among various stakeholders in an infinite-horizon setting with network effects, taking account of operational details. We show that uncapped ICOs weakly dominate capped ones in...