# x402 Swap

> Free quotes. One cent to build. 10 bps included when you swap.

x402 Swap returns executable unsigned cross-chain swap transactions through direct THORChain and MAYAChain integrations. Quotes and tracking are free. Successful unsigned transaction construction costs $0.01 USDC through x402 exact payment on Base or Solana. Every quote enforces the requested maximum slippage (300 bps by default), reports pool-depth checks, and includes a transparent 10 bps service fee. An optional protocol affiliate address can receive 3 bps from that included fee; no affiliate is required. Raw addresses need no x402 Swap registration, but a short THORName/MAYAName may be needed for a constrained memo; inspect the quote's affiliate disclosure.

## Agent workflow

1. POST https://x402swaps.com/v1/quotes for free, or call the free MCP tool get_swap_quote.
2. Select an opaque routeHandle from the all-in quote after checking liquidity, minimum output, and affiliate status.
3. POST https://x402swaps.com/v1/swaps/build with Idempotency-Key, sourceAddress, destinationAddress, and routeHandle, or call build_swap_transaction. This step costs $0.01 only when construction succeeds.
4. If build returns route_liquidity_changed or no_safe_route, wait retryAfterSeconds and request a new free quote with the same slippage limit. Never raise the limit without user authorization.
5. Sign and broadcast the returned transaction outside this service.
6. POST https://x402swaps.com/v1/swaps/track with the returned trackingToken and the first transaction hash.

## Interfaces

- OpenAPI: https://x402swaps.com/openapi.json
- MCP Streamable HTTP: https://x402swaps.com/mcp
- x402 discovery: https://x402swaps.com/.well-known/x402
- Supported assets: https://x402swaps.com/v1/assets

Phase 1 source construction supports native BTC, native SOL through THORChain, and supported EVM chains. The asset list distinguishes canSell from canBuy.

The fixed fee purchases successful transaction construction, not swap completion. Signing, broadcast, gas, provider execution, and refunds remain outside this service's control.