DeFi Relay Quoter - Pay-per-use 0x Swap API

This service provides access to 0x swap API using the x402 payment protocol.

PRICING:
  Price endpoints (indicative):  500 raw USDC per request
  Quote endpoints (full quote):  1000 raw USDC per request

ENDPOINTS:

  Permit2 (requires Permit2 approval):
    GET /swap/permit2/price  - Get indicative price
    GET /swap/permit2/quote  - Get full quote with transaction data

  AllowanceHolder (single signature, recommended):
    GET /swap/allowance-holder/price  - Get indicative price
    GET /swap/allowance-holder/quote  - Get full quote with transaction data

REQUIRED QUERY PARAMETERS:
  chainId     - Chain ID (e.g., 1 for Ethereum, 8453 for Base)
  sellToken   - Address of token to sell (use 0xeee...eee for native ETH)
  buyToken    - Address of token to buy
  sellAmount  - Amount to sell in smallest unit (wei) - OR use buyAmount
  taker       - Address that will execute the swap

OPTIONAL PARAMETERS:
  buyAmount        - Amount to buy (alternative to sellAmount)
  slippageBps      - Slippage tolerance in basis points (e.g., 100 = 1%)
  excludedSources  - Liquidity sources to exclude
  includedSources  - Liquidity sources to include

EXAMPLE REQUEST:
  GET /swap/permit2/quote?chainId=1&sellToken=0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee&buyToken=0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48&sellAmount=1000000000000000000&taker=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
  Header: X-PAYMENT: <base64-encoded-x402-payment>

OTHER ENDPOINTS:
  GET  /                   - This help page
  GET  /health             - Health check
  GET  /agent.json         - EIP-8004 agent metadata
  GET  /.well-known/x402   - x402 discovery document

PERMIT2 vs ALLOWANCE-HOLDER:
  - AllowanceHolder: Single signature, better UX, lower gas. Recommended for most use cases.
  - Permit2: Universal standard, shared approvals across apps, requires two signatures.

SUPPORTED CHAINS:
  - Ethereum (1)
  - Base (8453)
  - Arbitrum (42161)
  - Optimism (10)
  - Polygon (137)
  - Avalanche (43114)
  - BSC (56)

For more info on x402: https://www.x402.org
For 0x API docs: https://0x.org/docs/api