⚡️ Flash Lending

Borrow Ether and ERC20 tokens to take advantage of arbitrage opportunities on Ethereum.

How it Works

We supply Ether and tokens in a smart contract called Bank. This contract is currently deployed on the Ethereum mainnet in public beta with a balance of 2 Ether.

FlashLender is an approved borrower of the bank. It has a method called

borrow

A smart contract can execute any arbitrary code after calling

borrow

executeArbitrage

isArbitrage

This lets anyone profit from an arbitrage opportunity on Ethereum without using their own capital. The arbitrageur simply pays for the gas cost of the transaction.

Quick Start: DEX Arbitrage

Flash Lender can be used to execute arbitrage trades on decentralized exchanges.

We deployed Arbitrage, TradeExecutor, and several exchange wrappers to support this use case.

• Arbitrage

  borrows from FlashLender and sends trade data to TradeExecutor

• TradeExecutor

  executes the trades on the appropriate exchange wrappers
• Exchange wrappers contain all of the logic required to convert Ether to tokens and vice versa on a given decentralized exchange. For example,

  ZeroExWrapper

  converts Ether to wrapped ETH (WETH) and then uses the 0x exchange contract to swap WETH for another ERC20 token.

We can only support exchanges that allow smart contracts to execute orders. This includes 0x, Bancor, Kyber, and EtherDelta.

If you would like to add an additional exchange integration, please submit a pull request!

If you decide to use this set of smart contracts, this is the basic architecture:

Make a Trade

1. Find a buy and sell order with an arbitrage profit. Most exchanges have a public API that can be used for this step, like Radar Relay.
2. Encode the buy order on the appropriate exchange wrapper. For example:

   zeroExWrapperContract.methods.getTokens(orderAddresses, orderValues, v, r, s).encodeABI();
   

3. Encode the sell order on the appropriate exchange wrapper.
4. Encode the

   trade

   method on

   TradeExecutor

   using the encoded buy as

   trade1

   and the encoded sell as

   trade2

   .
5. Use the result as the data parameter for

   submitTrade

   on

   Arbitrage

   , along with the token to borrow, amount to borrow, and address to send the profits.

We recommend a gas limit of 1 million in order to accomodate exchanges like Bancor that consume a relatively high amount of gas.

See the arbitrage integration tests for a code example.

Testing

In a separate terminal tab, run a local blockchain with Ganache.

npm run chain

Run the tests.

npm run test

Contracts

The smart contracts below were deployed at commit

8df2f0d34feb65eeec34f3760673d9d21ad146aa

Bank.sol: 0xa04e5b78fbd31caec8f8af126d00a57f56c1f7ae

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FlashLender.sol: 0x57d586906cb1b995dfce24730906f59d60490ff6

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Arbitrage.sol: 0xea94f0fffaa4f1c17ba190f5df3b738edcd43228

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TradeExecutor.sol: 0x66c16e9524e4143c63fca51a2cbe3cc18944c794

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Exchange Wrappers

BancorWrapper.sol: 0xd66eba2f90a1dd296736d8b8ac39602200700165

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ZeroExWrapper.sol: 0x7c5475e3adfe4dab7253ae27727a60a2a3638834

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KyberWrapper.sol: 0xf1b94902aa8eeff8b973877e835651b86a3a4a89

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EtherDeltaWrapper.sol: 0x9183d15070772dfd4524321d000da9b213736d90

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