Uniswap V3 Swaps

Multi-hop swaps route through sequential pools, with the SwapRouter encoding the path and executing callbacks at each pool to transfer tokens and calculate liquidity changes across ticks. Fee tier selection affects slippage and execution price.

exactInput specifies the token amount you send and outputs the minimum received after accounting for slippage. exactOutput reverses this: you specify the token amount you want and pay the maximum required, protecting against excessive input costs.

Trace the swap through each pool's tick structure, applying liquidity and price range dynamics at each step. The SwapRouter periphery handles callback mechanics automatically, but understanding tick transitions lets you reason about intermediate outputs and slippage accumulation.

Multi-hop swaps compound slippage across pools and introduce callback delays where liquidity may shift between ticks. Setting minimum output thresholds prevents partial fills at unfavorable prices, especially during volatile market conditions.

Single-pool swaps work for direct token pairs and are simpler to reason about. Cross-pool routing becomes necessary when no direct pool exists for your token pair or when fee tier combinations offer better execution.

Callbacks allow pools to request token transfers from the caller during swaps. The SwapRouter uses callbacks to abstract pool interactions, enabling atomic multi-hop execution and reducing transaction overhead compared to sequential approvals.