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Cross-chain Swaps with Symbiosis
Cross-chain swapping with the Symbiosis protocol in a nutshell.
The Symbiosis protocol was born for cross-chain operations. In the beginning, it was cross-chain swaps and bridging; then, we added more functions to our protocol: interchain communicating and cross-chain zaps. This document explains how the Symbiosis protocol handles the cross-chain swap operation that includes bridging (mining/burning sTokens).
While doing a cross-chain swap with Symbiosis protocol V2, three cases are possible:
- 1.The source and destination chains of a cross-chain swap are not S-Chain (Scheme 1),
- 2.The destination blockchain of a cross-chain swap is S-chain (Scheme 2),
- 3.The source blockchain of a cross-chain swap is S-chain (Scheme 3).
The source and destination blockchains of a cross-chain operation are not S-Chain.
As an example, let's see how a cross-chain swap MATICs for AVAXes goes with Symbiosis V2 (Scheme 1).

Scheme 1: A cross-chain swap MATICs for AVAXes with Symbiosis protocol V2
Important notices for Scheme 1
Steps 6 and 10. The Symbiosis protocol mints/releases tokens with a ratio of 1:1 and then withholds an amount that equals the transaction processing fee on the current blockchain. For more details on the fee withholding process, please refer to Gas Fees for Cross-chain Operations via Symbiosis
Step 11. Once the last on-chain swap is accomplished, the user gets tokens to their address on the destination chain.
The destination blockchain of a cross-chain operation is S-chain.
As an example, let's see how a cross-chain swap MATICs on Polygon for BOBAs on BOBA BNB goes with Symbiosis (Scheme 2).

Scheme 2: A cross-chain swap with the Symbiosis protocol V2 (MATICs on Polygon for BOBAs on BOBA BNB).
Important notices for Scheme 2
Step 6. The Symbiosis protocol mints tokens with a ratio of 1:1 and then withholds an amount that equals the transaction processing fee on the current blockchain. For more details on the fee withholding process, please refer to Gas Fees for Cross-chain Operations via Symbiosis
Step 8. Since there are no DEX aggregators on BOBA BNB, Symbiosis uses existing DEXes for on-chain swaps on BOBA BNB. Once the last on-chain swap is accomplished, the user gets tokens to their address on the destination chain.
The source blockchain of a cross-chain operation is S-chain.
As an example, let's see how a cross-chain swap BOBAs on BOBA BNB for AVAXs on Avalanche goes with Symbiosis V2 (Scheme 3).

Scheme 3: A cross-chain swap with the Symbiosis protocol V2 (BOBAs on BOBA BNB for AVAXs on Avalanche).
Important notices for Scheme 3
Step 2. Since there are no DEX aggregators on BOBA BNB, Symbiosis uses existing DEXes for on-chain swaps on BOBA BNB.
Step 10. The Symbiosis protocol releases tokens with a ratio of 1:1 and then withholds an amount that equals the transaction processing fee on the current blockchain. For more details on the fee withholding process, please see Gas Fees for Cross-chain Operations via Symbiosis.
The lifespan of Symbiosis protocol V1 has peacefully reached its end, and we stopped it. The information below is for historical records about the Symbiosis protocol development.
The Symbiosis protocol V1 has one Nerve-like liquidity pool {stablecoin, sToken} for every blockchain pair that supports direct cross-chain operations. Such a liquidity pool is located on the blockchain with the loweer gas fee (in the USD equivalent) to minimize expenses related to the transaction cost.
While doing a cross-chain swap with Symbiosis protocol V1, two cases are possible:
- 1.There is no Symbiosis liquidity pool {stablecoin, sToken} on the source blockchain of cross-chain swap (Scheme 4).
- 2.There is a Symbiosis liquidity pool {stablecoin, sToken} on the source blockchain of cross-chain swap (Scheme 5).
Consider an example of a cross-chain swap from a blockchain with a high gas fee to a blockchain with a lower gas fee (in USD equivalent), so there is no Symbiosis liquidity pool {stablecoin, sToken} on the source blockchain of cross-chain swap.
As an example, let's see how a cross-chain swap UNI on Ethereum for CAKE on the BNB chain goes with Symbiosis V1 (Scheme 4).
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Scheme 4. the UNI → CAKE cross-chain swap with Symbiosis protocol V1.
Consider an example of a cross-chain swap from a blockchain with a low gas fee to a blockchain with a high gas fee (in USD equivalent), so there is a Symbiosis liquidity pool {stablecoin, sToken} on the source blockchain of cross-chain swap.
As an example, let's see how a cross-chain swap CAKE on the BNB chain for UNI on Ethereum goes with Symbiosis V1 (Scheme 5).
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Scheme 5. the CAKE -> UNI cross-chain swap with the Symbiosis protocol V2.
Symbiosis uses the Ren Protocol on BNB Chain and Polygon to perform cross-chain exchanges for BTC. When the Ren Protocol receives renBTCs, it burns them and sends BTCs to the user's address on BITCOIN BLOCKCHAIN.
Thus, Symbiosis acts as the interchain communicating protocol while exchanging for BTC, so please refer to Symbiosis as Interchain Communication Protocol section Exchanging for BTC for more information about this process.