I Deployed a Flash Loan Arbitrage Bot on Polygon Mainnet — Here’s Everything I Learned

A self-taught developer shares a hands-on account of building and deploying a flash loan arbitrage bot on Polygon mainnet. The contract borrows USDC from Aave v3, routes trades through QuickSwap (Algebra-based) and Uniswap V3, and repays the loan atomically. Key technical lessons include the interface differences between Uniswap V3 and Algebra routers, the importance of slippage protection, and the need for a profit guard. The honest takeaway: the code works, but profitable spreads almost never exist because MEV bots have already arbitraged them away. The post emphasizes the value of deploying to mainnet over just reading tutorials.