Owlto SDK

If you are Aggregators, Cross-Chain Swap, DEX, etc., you can choose to install Owlto-SDK as your underlying solution to achieve cross-chain functionality between different networks.

Install

# Use yarn
yarn add owlto-sdk

# Or use npm
npm install owlto-sdk --save

Quickstart

For example, to bridge USDC from Base to Scroll

import * as owlto from "owlto-sdk";

const options: owlto.BridgeOptions = {}
let bridge = new owlto.Bridge(options);

const result = await bridge.getBuildTx(
    "USDC", //token name
    "BaseMainnet", //from chain name
    "ScrollMainnet",// to chain name
    "1", // value
    "0xa5E56D455BF247C475D752721Ba35A0c85Df81Dc", // from address
    "0xa5E56D455BF247C475D752721Ba35A0c85Df81Dc", // to address
);

//initialize your wallet
//...

if (result.txs.approveBody) {
    const tx = await wallet.sendTransaction(result.txs.approveBody as ethers.TransactionRequest);
    await tx.wait(); 
}

const tx = await wallet.sendTransaction(result.txs.transferBody as ethers.TransactionRequest);
await tx.wait(); 

const receipt = await bridge.waitReceipt(tx.hash)
console.log(receipt)

For more details, check the example/bridge_usdc folder.

Bridge options

1.chainNameMapping (Map<string, string> | optional)

Map your the chain names from your protocol with Owlto.

For example, if the chain name of Base Mainnet on your protocol is "Base", you can set chainNameMapping["Base"] = "BaseMainnet".

Then you can run functions with chain name as "Base" in order to proceed with a bridge.

Get build tx

const result = await bridge.getBuildTx(
    "USDC", //token name
    "BaseMainnet", //from chain name
    "ScrollMainnet",// to chain name
    "1", // value
    "0xa5E56D455BF247C475D752721Ba35A0c85Df81Dc", // from address
    "0xa5E56D455BF247C475D752721Ba35A0c85Df81Dc", // to address
);

//result:
{
 ...
  networkType: 1; //
  txs: any; //actual transactions need to be sent to from chain, see the following details
}

The txs contains the transactions user should send to from chain when bridging.

1.Evm

txs.approveBody
The approve transaction, if any, should be sent first.
txs.transferBody
The actual transfer transaction.

2.Starknet

Coming Soon

3.Solana

Coming Soon

Get receipt

bridge.waitReceipt(fromChainHash: string)
bridge.getReceipt(fromChainHash: string)

fromChainHash is the hash value of the transfer transaction.

waitReceipt refers to waiting for the bridge process to complete.

If the bridge process is not completed within 1 minute (usually due to not finding the hash value or failure), error message will be displayed.

getReceipt refers to get the status of a bridge process.

If fromChainHash is not found, bridge is in progress or failed, error message will be displayed.

Get pair info

bridge.getPairInfo(tokenName: string, fromChainName: string, toChainName: string)
bridge.getAllPairInfos()

A pair consists of three components: token name, from chain name, to chain name.

You can only bridge supported pairs

HTTP API Documentation

The URL path for API: https://owlto.finance/api/bridge_api/v1/{API}

Documentation: https://owlto.finance/bridge_api/v1/swagger/index.html

Q&A

How do I know which tokens can be bridged between selected chains?

You can simply called the bridge.getAllPairInfos() function.(get_all_pair_infos HTTP API)

It will return a list of pairs for each supported tokens can be bridged.

What does build tx do?

The bridge.getBuildTx() function(get_build_tx HTTP API) will return all the transactions needed when bridging.

For example, if you bridge USDC from Base to Scroll, it will return two transactions in the txs field.

txs.approveBody, approve to Owlto smart contract.(will be null if the allowance is enough)
txs.transferBody, transfer the USDC token to Owlto smart contract on Base chain.

The transactions are in ETH JSON format and are ready to be sent by library like "Ethers".

Why getReceipt () returns error?

The bridge.getReceipt() function(get_receipt HTTP API) will return the status of the bridge process.

When it return non zero code, there are typically three cases

The hash you request is not found, maybe the user failed to send the txs.transferBody or there is a delay.
The hash you request is found, but the bridge process is still ongoing, you should try again later.
The hash you request is found, but the bridge process failed due to reasons like value out of range.

owlto-finance/owlto-sdk