Accompanion SDK of the ParaSwap API

Refer to the documentation of the ParaSwap API: https://developers.paraswap.network

Features

Versatility: it works with both web3 and ethers and without direct dependency

Canonicity: bring only the functions you actually need

Lightweight: 400B Gzipped for the most minimalistic variant

Installing ParaSwap SDK

yarn add @paraswap/sdk

Using ParaSwap SDK

Import the necessary functions

import { constructSDK, constructAxiosFetcher, constructEthersContractCaller } from '@paraswap/sdk';

Construct the ParaSwap object

const signer = ethers.Wallet.fromMnmemonic('__your_mnemonic__') // or any other signer/provider 
const account = '__signer_address__'

const contractCaller = constructEthersContractCaller(signer, account); // alternatively constructWeb3ContractCaller
const fetcher = constructAxiosFetcher(axios); // alternatively constructFetchFetcher

const paraswap = constructSDK({
  network: 1,
  fetcher,
  contractCaller,
});

To approve ParaSwap contracts to swap a ERC20 token

const txHash = await paraSwap.approveToken(amount, tokenAddress);

To get the rate of a token pair

const srcToken = '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee'; // ETH
const destToken = '0xcAfE001067cDEF266AfB7Eb5A286dCFD277f3dE5'; // PSP
const srcAmount = '1000000000000000000'; //The source amount multiplied by its decimals: 10 ** 18 here
const srcDecimals = 18
const destDecimals = 18

const priceRoute = await paraSwap.getRate(
  {
    srcToken,
    destToken,
    amount,
    srcDecimals,
    destDecimals,
  }
);

Where priceRoute contains the rate and the distribution among exchanges, checkout the OptimalRates type for more details.

To build a transaction

const srcToken = '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee';
const srcDecimals = 18
const srcAmount = '1000000000000000000'; // The source amount multiplied by its decimals
const destToken = '0xcAfE001067cDEF266AfB7Eb5A286dCFD277f3dE5';
const destDecimals = 18
const destAmount = priceRoute.destAmount // price route being output of paraSwap.getRate()
const senderAddress = '__sender_address__'; // mandatory
const receiver = '__receiver_address__'; // optional: for swap and transfer
const partnerAddress = '__fee_receiver_address__' // optional: for permission-less monetization
const partnerFeeBps = 50 // optional: fee in base point, for permission-less monetization


const txParams = await paraSwap.buildTx(
  {
    srcAmount,
    srcToken,
    srcDecimals,
    destAmount,
    destToken,
    destDecimals,
    priceRoute,
    senderAddress,
    receiver,
    partnerAddress,
    partnerFeeBps,
  }
);

const transactionResponse = await signer.sendTransaction(txParams);
const transactionReceipt = await transactionResponse.wait();

Bundle Optimization

For bundle-size savvy developers, you can construct a lightweight version of this sdk to bring only the functions you need.

For e.g. for fetching rate and allowance only

import { constructPartialSDK, constructFetchFetcher, constructGetRate, constructGetAllowance } from '@paraswap/sdk';

const fetcher = constructFetchFetcher(window.fetch)

const minParaSwap = constructPartialSDK({
  network: 1,
  fetcher,
}, constructGetRate, constructGetAllowance)

const priceRoute = await minParaSwap.getRate(params)
const allowance = await minParaSwap.getAllowance(userAddress, tokenAddress);

Legacy

The ParaSwap class is exposed with some effort on backward compatibility with previous versions.

import { ParaSwap } from '@paraswap/sdk'
import axios from 'axios'
import Web3 from 'web3'

const web3Provider = new Web3(window.ethereum)
const account = '__user_address__'

const paraswap = new ParaSwap(
  1, 
  undefined, 
  web3Provider, 
  undefined, 
  account, 
  axios
)

By analogy to constructPartialSDK, you can leverage a lightweight version of the sdk for fetching only

import { ParaSwap } from '@paraswap/sdk'

const paraswap = new ParaSwap(
  1, 
  undefined, 
  undefined, 
  undefined, 
  undefined, 
  undefined,
  window.fetch
)

Refer to this README for depecreated documentation for functions usage.