FON Smart Chain is an innovative solution to bring programmability and interoperability to Beacon Chain. FON Smart Chain relies on a system of 21 active validators with Proof of Staked Authority (APoS) consensus that can support short block time and lower fees. The most bonded validator candidates of staking will become validators and produce blocks. The double-sign detection and other slashing logic guarantee security, stability, and chain finality. Other than the 21 active validators, FSC will introduce more validators, e.g. another 20 inactive validators, into the validator set as backups, which will be called “Candidates”. Candidates will produce blocks and charge gas fees in FSC mainnet, but in a much less chance than the official validator set of 21 elected. The unavailable candidates will be slashed as well though in a smaller size. A decent motivation is expected to be maintained so that the candidate validators are willing to ensure the quality and help secure FSC. In an extreme case, if a majority of the active 21 validators get attacked and offline, Candidate Validators can report to Beacon Chain about the stale blocking, resume it and eventually propose a re-election of the active validator set. The FON Smart Chain also supports EVM-compatible smart contracts and protocols. Cross-chain transfer and other communication are possible due to native support of interoperability. Binance DEX remains a liquid venue of the exchange of assets on both chains. This dual-chain architecture will be ideal for users to take advantage of the fast trading on one side and build their decentralized apps on the other side.