profitable-flashloans

WATCH BLOCKS. SPOT ARBITRAGE. BORROW. PROFIT.

profitable-flashloans is a DeFi arbitrage bot that listens to new Ethereum blocks, compares DAI/WETH prices across Kyber and Uniswap, and fires a dYdX flash loan the moment a spread covers gas. No capital required — the loan is borrowed, swapped, and repaid inside a single atomic transaction.

If the trade is not profitable end-to-end, the transaction reverts and you lose nothing but gas estimation cycles.

Getting Started · How It Works · Configuration · Layout · Disclaimer

Quick Start

Runtime: Node 16 (pinned in package.json#engines). Toolchain: Truffle for contract compilation and migration.

git clone https://github.com/DeanShaked/profitable-flashloans.git
cd profitable-flashloans
npm install
npm start

The bot connects over a WebSocket provider, subscribes to newBlockHeaders, and prints arbitrage checks on every new block.

Prerequisites

• Node.js 16 — required (web3 + truffle pinning)
• Truffle — for compiling and deploying contracts/Flashloan.sol
• Ethereum WebSocket endpoint — Infura, Alchemy, or your own node
• Funded mainnet account — to pay gas on flash loan executions
• Public node providers are slow and front-runnable. For real use, run your own node.

Environment Setup

Create a .env file at the project root:

INFURA_URL=wss://mainnet.infura.io/ws/v3/YOUR_PROJECT_ID
PRIVATE_KEY=0xyour_private_key_here

Then compile and migrate the flash loan contract:

truffle compile
truffle migrate --network mainnet

How It Works

flowchart TB
  env[".env<br/>INFURA_URL + PRIVATE_KEY"]
  abis["abis/<br/>kyber ABI"]
  addr["addresses/<br/>kyber, uniswap, dydx, tokens"]

  subgraph Bot["run-arbitrage.js — Node bot"]
    sub["web3.eth.subscribe('newBlockHeaders')"]
    price["Price oracle loop<br/>updateEthPrice() every 15s"]
    quote["Quote DAI -> WETH on both DEXes"]
    check["Profit check<br/>output > input + gasCost"]
    fire["Send flash loan tx"]
  end

  subgraph Chain["Ethereum mainnet"]
    fl["Flashloan.sol<br/>contracts/Flashloan.sol"]
    dydx["dYdX Solo Margin<br/>flash loan source"]
    kyber["Kyber Network Proxy"]
    uni["Uniswap V2 Router"]
  end

  env --> Bot
  abis --> Bot
  addr --> Bot

  sub --> quote
  price --> check
  quote --> check
  check -->|profitable| fire
  fire --> fl
  fl --> dydx
  dydx -->|borrows DAI| fl
  fl -->|swap leg 1| kyber
  fl -->|swap leg 2| uni
  fl -->|repay loan| dydx

Loading

On every new block the bot:

1. Fetches DAI→WETH and WETH→DAI quotes from Kyber and Uniswap for a fixed AMOUNT_DAI_WEI (20,000 DAI by default).
2. Estimates gas cost in DAI using the live ETH price.
3. If output - input - gasCost > 0 for either direction, calls Flashloan.initiateFlashloan(...) with the trade direction (KYBER_TO_UNISWAP or UNISWAP_TO_KYBER).
4. The contract borrows DAI from dYdX Solo, executes both swap legs, repays the loan, and keeps the spread — atomically in a single transaction.

If any leg fails or profit evaporates between estimation and execution, the entire transaction reverts.

Configuration

The arbitrage parameters are set as constants near the top of run-arbitrage.js.

Constant	Default	Purpose
AMOUNT_DAI_WEI	20000 DAI	Notional size of the flash loan, in wei
ONE_WEI	1 ETH (wei)	Scaling unit for BN math
DIRECTION	enum	KYBER_TO_UNISWAP = 0, UNISWAP_TO_KYBER = 1
Polling	every 15s	updateEthPrice() interval, used to value gas in DAI

Token and exchange addresses live in addresses/ and ABIs in abis/.

Project Layout

.
├── contracts/
│   ├── Flashloan.sol           # dYdX-callback contract executing the arb
│   ├── IUniswapV2Router01.sol  # Uniswap router interface
│   ├── IUniswapV2Router02.sol  # Uniswap router interface
│   ├── IWeth.sol               # WETH wrap/unwrap interface
│   └── Migrations.sol          # Truffle bookkeeping
├── migrations/
│   ├── 1_initial_migration.js
│   └── 2_deploy_contracts.js
├── addresses/                  # Mainnet contract addresses (kyber, uniswap, dydx, tokens)
├── abis/                       # On-chain ABIs (kyber)
├── test/                       # Truffle test suite
├── run-arbitrage.js            # The bot — block subscription + decision loop
├── truffle-config.js           # Network + compiler config
├── Procfile                    # Process definition (e.g. for Heroku-style runners)
└── package.json

Scripts

Command	Description
npm start	Run the arbitrage bot (node run-arbitrage.js)
truffle compile	Compile Solidity contracts
truffle migrate	Deploy Flashloan.sol to the configured network
truffle test	Run the contract test suite

Arbitrage Specs

• Decentralized exchanges: Uniswap V2, Kyber Network
• Flash loan source: dYdX Solo Margin
• Tokens: DAI, WETH
• Network: Ethereum mainnet

More tokens, DEXes, and L2 networks are on the roadmap.

Disclaimer

Read this before running on mainnet

This project is experimental software and was originally written as a learning exercise. Running it on mainnet means:

• You are sending real transactions with a real private key on a real chain.
• Public RPC endpoints are slow and front-runnable — competing MEV bots with co-located nodes will beat you to most opportunities.
• Pricing data on the Ethereum mainnet has been heavily arbitraged; profitable spreads on DAI/WETH between Kyber and Uniswap are rare and brief.
• Failed transactions still cost gas.
• The dependency stack (web3@1, @uniswap/sdk@2, @studydefi/money-legos, Node 16) is outdated and may have unpatched issues.

Use at your own risk. Audit the contract before deploying. Test on a fork (e.g. Anvil, Hardhat mainnet fork) before sending real funds.

Project Docs

License

Contributing

References

License

Released under the ISC License. Free to use, modify, and distribute. Provided "as is" with no warranty.

Contributing

Issues and pull requests are welcome.

• Fork the repo and open a PR against main.
• Keep changes focused — separate refactors from feature work.
• If you add a new DEX or token pair, include the addresses and ABIs and update the Arbitrage Specs section.

References

• dYdX Solo flash loans — zero-fee atomic borrowing
• Uniswap V2 SDK — pair pricing and quotes
• Kyber Network Proxy — on-chain liquidity router
• @studydefi/money-legos — bundled DeFi interfaces and addresses