Swap quote (V1)

Below are the two methods to get a quote for a swap from a given route using JSON-RPC or REST-API:

When providing HBAR in the path array, use the wrapped HBAR token ID (WHBAR).

Get output quote from input amount

No gas cost — read-only call. Get the output amounts from a given input amount and a swap route. Function name: getAmountsOut

Parameter Name	Description
uint amountIn	The input token amount in its smallest unit
address[] path	An ordered list of token EVM addresses

function getAmountsOut(
  uint amountIn,
  address[] calldata path
) external view returns (uint[] memory amounts);

function getAmountsOut(uint amountIn, address[] memory path)
  public
  view
  virtual
  override
  returns (uint[] memory amounts)
{
  return UniswapV2Library.getAmountsOut(factory, amountIn, path);
}

Code overview

JSON RPC
REST API

Resources:

import * as ethers from 'ethers'; //V6

//Set one of Hedera's JSON RPC Relay as the provider
const provider = new ethers.JsonRpcProvider(hederaJsonRelayUrl, '', {
  batchMaxCount: 1, //workaround for V6
});

//ABI data for the getAmountsOut
const abi = ['function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts)'];

//Load the ABI
const abiInterfaces = new ethers.Interface(abi);

//Example route
const tokenIn = '0x' + TokenId.fromString(whbarTokenId).toSolidityAddress();
const tokenOut = '0x' + TokenId.fromString(sauceTokenId).toSolidityAddress();
const route = [tokenIn, tokenOut];

const routerContract = new ethers.Contract(routerEvmAddress, abiInterfaces.fragments, provider);
const result = await routerContract.getAmountsOut(inputAmountInSmallestUnit, route);
const amounts = result; //uint[] amounts
const finalOutputAmount = amounts[amounts.length - 1]; //in token's smallest unit

Resources:

import * as ethers from 'ethers'; //V6

//ABI data for the getAmountsOut
const abi = ['function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts)'];

//Load the ABI
const abiInterfaces = new ethers.Interface(abi);

//Example route (WHBAR > SAUCE)
const tokenIn = '0x' + TokenId.fromString(whbarTokenId).toSolidityAddress();
const tokenOut = '0x' + TokenId.fromString(sauceTokenId).toSolidityAddress();
const route = [tokenIn, tokenOut];

const routerContract = ContractId.fromString(routerContractId);
const params = [inputAmountInSmallestUnit, route];
const encodedData = abiInterfaces.encodeFunctionData(abiInterfaces.getFunction('getAmountsOut')!, params);

const url = `${mirrorNodeBaseUrl}/api/v1/contracts/call`;
const data = {
  'block': 'latest',
  'data': encodedData,
  'to': routerContract.toSolidityAddress(),
};

const response = await axios.post(url, data, { headers: {'content-type': 'application/json'} });
const amounts = abiInterfaces.decodeFunctionResult('getAmountsOut', response.data.result)[0]; //uint[] amounts
const finalOutputAmount = amounts[amounts.length - 1]; //in token's smallest unit

Get input quote from output amount

No gas cost — read-only call. Get the input amounts from a given output amount and a swap route. Function name: getAmountsIn

Parameter Name	Description
uint amountOut	The output token amount in its smallest unit
address[] path	An ordered list of token EVM addresses

function getAmountsIn(
  uint amountOut,
  address[] calldata path
) external view returns (uint[] memory amounts);

function getAmountsIn(uint amountOut, address[] memory path)
  public
  view
  virtual
  override
  returns (uint[] memory amounts)
{
  return UniswapV2Library.getAmountsIn(factory, amountOut, path);
}

Code overview

JSON RPC
REST API

Resources:

import * as ethers from 'ethers'; //V6

const networkId = 'testnet';
const provider = new ethers.JsonRpcProvider(`https://${networkId}.hashio.io/api`, '', {
  batchMaxCount: 1,
});

//ABI data for the getAmountsIn
const abi = ['function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts)'];

//Load the ABI
const abiInterfaces = new ethers.Interface(abi);

//Example route (WHBAR > SAUCE)
const tokenIn = '0x' + TokenId.fromString(whbarTokenId).toSolidityAddress();
const tokenOut = '0x' + TokenId.fromString(sauceTokenId).toSolidityAddress();
const route = [tokenIn, tokenOut];

const routerContract = new ethers.Contract(routerEvmAddress, abiInterfaces.fragments, provider);
const result = await routerContract.getAmountsIn(outputAmountInSmallestUnit, route);
const amounts = result; //uint[] amounts
const finalInputAmount = amounts[0]; //in token's smallest unit

Resources:

import * as ethers from 'ethers'; //V6

//ABI data for the getAmountsIn
const abi = ['function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts)'];

//Load the ABI
const abiInterfaces = new ethers.Interface(abi);

//Example route (WHBAR > SAUCE)
const tokenIn = '0x' + TokenId.fromString(whbarTokenId).toSolidityAddress();
const tokenOut = '0x' + TokenId.fromString(sauceTokenId).toSolidityAddress();
const route = [tokenIn, tokenOut];

const routerContract = ContractId.fromString(routerContractId);
const params = [outputAmountInSmallestUnit, route];
const encodedData = abiInterfaces.encodeFunctionData(abiInterfaces.getFunction('getAmountsIn')!, params);

const url = `${mirrorNodeBaseUrl}/api/v1/contracts/call`;
const data = {
  'block': 'latest',
  'data': encodedData,
  'to': routerContract.toSolidityAddress(),
};

const response = await axios.post(url, data, { headers: {'content-type': 'application/json'} });
const amounts = abiInterfaces.decodeFunctionResult('getAmountsIn', response.data.result)[0]; //uint[] amounts
const finalInputAmount = amounts[0]; //in token's smallest unit

Next steps

Swap HBAR for tokens (V1)

Execute the swap you just quoted with the V1 router.

Swap quote (V2)

Quote against V2 concentrated liquidity with QuoterV2.

Contract deployments

Router, factory, and token IDs for mainnet and testnet.

Getting started

V1 guides

V2 guides

V3 order book

More guides

Security

AI

Get output quote from input amount

Code overview

Get input quote from output amount

Code overview

Next steps

Swap HBAR for tokens (V1)

Swap quote (V2)

Contract deployments

​Get output quote from input amount

​Code overview

​Get input quote from output amount

​Code overview

​Next steps

Swap HBAR for tokens (V1)

Swap quote (V2)

Contract deployments

Get output quote from input amount

Code overview

Get input quote from output amount

Code overview

Next steps