TRN trades on Arbitrum, Base and Arc. We ask each pool what your USDC buys right now and send the order where it buys the most.
The same numbers, as JSON: GET /api/trn/prices for the price on every chain, and GET /api/trn/quote?usdc=5 for what an amount buys on each and which chain wins. Prices are read from the pools; a pool with nothing to trade against is reported as having no market.