@paraswap/sdk

SDK for the ParaSwap API

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

Features

Versatility: works with both web3 and ethers without direct dependency

Canonical: bring only the functions you actually need

Lightweight: 400B Gzipped for the minimal variant

Installing ParaSwap SDK

yarn add @paraswap/sdk

Using ParaSwap SDK

There are multiple ways to use ParaSwap SDK, ranging from a simple construct-and-use approach to a fully composable bring what you need approach which allows for advanced tree-shaking and minimizes bundle size.

Simple SDK

Can be created by providing chainId and either axios or window.fetch (or alternative fetch implementation). The resulting SDK will be able to use all methods that query the API.

  import { constructSimpleSDK } from '@paraswap/sdk';
  import axios from 'axios';

  // construct minimal SDK with fetcher only
  const paraSwapMin = constructSimpleSDK({chainId: 1, axios});
  // or
  const paraSwapMin = constructSimpleSDK({chainId: 1, fetch: window.fetch});

  const ETH = '0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee';
  const DAI = '0x6B175474E89094C44Da98b954EedeAC495271d0F';

  async function swapExample() {
    //                                     or any other signer/provider 
    const signer: JsonRpcSigner = ethers.Wallet.fromMnmemonic('__your_mnemonic__');
    const senderAddress = signer.address;

    const priceRoute = await paraSwapMin.swap.getRate({
      srcToken: ETH,
      destToken: DAI,
      amount: srcAmount,
      userAddress: senderAddress,
      side: SwapSide.SELL,
    });

    const txParams = await paraSwapMin.swap.buildTx(
      {
        srcToken,
        destToken,
        srcAmount,
        destAmount,
        priceRoute,
        userAddress: senderAddress,
        partner: referrer,
      }     
    );

    const transaction = {
      ...txParams,
      gasPrice: '0x' + new BigNumber(txParams.gasPrice).toString(16),
      gasLimit: '0x' + new BigNumber(5000000).toString(16),
      value: '0x' + new BigNumber(txParams.value).toString(16),
    };

    const txr = await signer.sendTransaction(transaction);
  }

If optional providerOptions is provided as the second parameter, then the resulting SDK will also be able to approve Tokens for swap.

  // with ethers.js
  const providerOptionsEther = {
    ethersProviderOrSigner: provider, // JsonRpcProvider
    EthersContract: ethers.Contract,
    account: senderAddress,
  };

  // or with web3.js
  const providerOptionsWeb3 = {
    web3, // new Web3(...) instance
    account: senderAddress,
  };

  const paraSwap = constructSimpleSDK({chainId: 1, axios}, providerOptionsEther);

  // approve token through sdk
  const txHash = await paraSwap.approveToken(amountInWei, DAI);

  // await tx somehow
  await provider.waitForTransaction(txHash);

Composed 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({
  ethersProviderOrSigner: signer,
  EthersContract: ethers.Contract,
}, account); // alternatively constructWeb3ContractCaller
const fetcher = constructAxiosFetcher(axios); // alternatively constructFetchFetcher

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

To approve ParaSwap contracts to swap an ERC20 token

// if created with constructEthersContractCaller
const contractTx: ContractTransaction = await paraSwap.approveToken(amount, tokenAddress);
const txReceipt = await contractTx.wait();

// if created with constructWeb3ContractCaller
const unpromiEvent: Web3UnpromiEvent = await paraSwap.approveToken(amount, tokenAddress);
const txReceipt = await new Promise<Web3TransactionReceipt>((resolve, reject) => {
  unpromiEvent.once('receipt', resolve);
  unpromiEvent.once('error', reject);
})

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: srcAmount,
    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 the SDK and bring only the functions you need.

e.g. for only getting rates and allowances:

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

const fetcher = constructFetchFetcher(window.fetch);

const minParaSwap = constructPartialSDK({
  chainId: 1,
  fetcher,
}, constructGetRate, constructGetBalances);

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

Legacy

The ParaSwap class is exposed for backwards compatibility with previous versions of the SDK.

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({chainId: 1, web3Provider, account, axios});

Or you can use ethers in place of web3

import { ParaSwap } from '@paraswap/sdk';
import { ethers } from "ethers";

const ethersProvider = new ethers.providers.Web3Provider(window.ethereum)
const account = '__user_address__';

const paraswap = new ParaSwap({
  chainId: 1,
  account,
  ethersDeps: {
    ethersProviderOrSigner: ethersProvider;
    EthersContract: ethers.Contract;
  },
  fetch: window.fetch,
 });

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({chainId: 1, fetch: window.fetch});

Refer to this README for depecreated documentation for functions usage.

Refer to SDK API documentation for detailed documentation on the methods provided in this SDK.

Tests

To run yarn test it is necessary to provide PROVIDER_URL=<mainnet_rpc_url> environment variable. If it is necessary to run tests against a different API endpoint, provide API_URL=url_to_API environment variable.