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Symbiosis Core Smart Contracts
Symbiosis core smart contracts overview.
- Symbiosis core smart contracts are open source and available at https://github.com/symbiosis-finance/core-contracts
Symbiosis core smart contracts implement the on-chain logic of cross-chain operations (cross-chain swaps, cross-chain zaps, interchain communication, bridging). The smart contracts are deployed and tuned by Symbiosis administrators while adding a blockchain to the Symbiosis protocol.
The Symbiosis protocol has three slightly different sets of smart contracts: Scheme 1.

Scheme 1. The core smart contracts of the Symbiosis protocol.
All smart contracts shown in Scheme 1, except MulticallRouter and Octopool, are inherited from Symbiosis protocol V1 without a modification. Let's see what each contract does:
- 1.The MetaRouterGateway contract secures the interactions of the MetaRouter contract with users’ ERC20 tokens. Users’ ERC20 tokens should only be approved for this contract.
- 2.The MetaRouter contract manages calls to other Symbiosis contracts on one blockchain within one cross-chain operation.
- 3.The Portal contract locks and unlocks users' stablecoins during cross-chain operations.
- 4.The BridgeV2 contract is a proxy between the Symbiosis relayers network and the Synthesis/Portal contracts.
- 5.The Synthesis contract on S-chain mints and burns sTokens during cross-chain operations. The Synthesis contract on the BNB chain mints and burns sSIS tokens when bridging SIS tokens.
- 6.Symbiosis Octopool is a Symbiosis AMM with multiple tokens. There are two Symbiosis Octopools on Boba BNB: one with sStable tokens and the another one with sWETH tokens.
- 7.The MulticallRouter contract manages calls to Symbiosis contracts on Boba BNB (S-chain) within one cross-chain operation, when S-chain isn't the source or destination blockchain of the cross-chain operation.
- 8.Uniswap-like DEX {SIS BNB / BNB}: Symbiosis owns a Uniswap-like DEX with a {SIS BNB / BNB} pair on the BNB chain, allowing users to trade SIS tokens on the BNB chain.
Symbiosis Routing Contracts document explains how the contracts interact during cross-chain operations.
- Here is an explanation of how the Symbiosis protocol handles cross-chain operations Symbiosis Routing Contracts.