Blockchain and smart contract technologies were recently introduced. Due to their short histories, many issues have emerged but
are not solved yet. In this article, we summarize the currently concentrated issues under developing with regards to smart contracts:
vulnerability and cost optimization. We introduce other issues never considered but essential for successful commercialization of
the smart contract technology. Also, we verify that the optimized code of smart contracts can significantly save transactions costs.
Finally, we address that the cost-optimized design is affected by the platform type of blockchain systems. So, the vulnerability and
cost analysis of smart contracts must consider the blockchain platform to be deployed.