> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polygon.technology/llms.txt
> Use this file to discover all available pages before exploring further.

# Swap & bridge

> Let customers move and convert funds across any network in a single step, without managing bridges or liquidity yourself.

Cross-chain asset movement is one of the hardest infrastructure problems to build in-house. Your customers may hold ETH on Ethereum, but your product settles in USDC on Polygon. They may receive a payout in one token and want another. Getting from one to the other typically requires multiple transactions, gas on every chain involved, and UX that stops most users cold.

Cross-chain payments handle the entire path (routing, bridging, and swapping) in a single customer action.

## What this enables

**Token conversion at settlement**: Accept any token from customers and settle in the token your product uses. A customer paying with ETH can send the exact USDC equivalent to your contract on Polygon, without a separate conversion step.

**Cross-network fund movement**: Move customer funds between networks as part of normal product operations, without your team managing bridge infrastructure or liquidity positions.

**Portfolio rebalancing**: Let customers rebalance holdings across chains in one action. They specify what they want to end up with; the routing layer finds the optimal route.

**FX-like stablecoin conversion**: Swap between stablecoins across networks (e.g., USDT on Tron to USDC on Polygon) as a backend settlement primitive.

## How it works

The routing layer handles bridges and DEXs automatically, finding the best path for each transfer. You specify the source and destination; it handles what happens in between.

```tsx theme={null}
import { Swap } from "0xtrails";

<Swap
  apiKey="YOUR_API_KEY"
  from={{
    token: "ETH",
    chain: "ethereum",
  }}
  to={{
    token: "USDC",
    chain: "polygon",
    amount: "500", // exact output: user receives exactly 500 USDC
  }}
  onSwapSuccess={(result) => console.log("Settled:", result)}
/>
```

The customer selects how much to send. The SDK quotes the route, the customer confirms once, and funds arrive on Polygon as USDC.

## Exact input vs. exact output

Two trade modes cover the main product scenarios:

| Mode         | Use when                                                                    |
| ------------ | --------------------------------------------------------------------------- |
| Exact input  | Customer specifies how much to send; they receive whatever that converts to |
| Exact output | Customer receives a fixed amount; they pay whatever is required             |

Exact output is the right model for payments and settlements where the destination amount must be precise. Exact input suits exchange and conversion flows where the customer controls the spend.

## Headless integration

For custom UIs or server-driven flows, use `useQuote` to get a route and execute it programmatically:

```tsx theme={null}
import { useQuote } from "0xtrails";

const { quote, loading } = useQuote({
  from: {
    chainId: 1,
    tokenAddress: "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2", // WETH on Ethereum
    amount: "0.5",
  },
  to: {
    chainId: 137,
    tokenAddress: "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359", // USDC on Polygon
    recipient: "0xSETTLEMENT_ADDRESS",
  },
});

if (quote) {
  await quote.send();
}
```

For a full reference on quote parameters and swap configuration, see the [Swap component](/cross-chain/sdk/swap) and [API reference](/cross-chain/api-reference/overview).