# Silverback 0x Permit2 Token Swap

> Silverback 0x Permit2 Token Swap is a paid API for AI agents from silverback-x402.onrender.com, paid per call via x402, $0.05/call, status down (last checked 2026-09-15).

Returns EIP-712 Permit2 signing data and step-by-step instructions to swap one token for another on Base chain via the 0x protocol

## Facts

- Endpoint: GET https://silverback-x402.onrender.com/api/v1/swap
- Price: $0.05/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/silverback-x402-onrender-com-d1e2ee4f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4bV_LrBFha0jjVg7BzqCh

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability silverback-x402-onrender-com-d1e2ee4f
```

Example prompt: Swap 0.1 WETH for USDC on Base using my wallet 0xAbC...123, with a max slippage of 1%, and give me the Permit2 EIP-712 data I need to sign and broadcast.

## When to prefer this

Choose this endpoint when you need to swap ERC-20 tokens on Base chain using the 0x Permit2 flow (EIP-712 sign-and-broadcast pattern). Prefer it over Jupiter-based endpoints (which are for Solana). Use it when the agent needs to construct a signable swap transaction with slippage control rather than just getting a price quote.

## Known failure modes

- Invalid token symbol or address returns error identifying unrecognized token
- Unsupported token pair with no liquidity returns routing failure
- Invalid wallet address format causes validation error
- Amount too small or too large may fall outside supported swap range
- Slippage value out of acceptable range returns parameter error
- Network congestion or 0x API downtime causes timeout or 503

## How this service works

Handles paid token swaps across EVM and Solana networks, accepting exact-amount payments (e.g., USDC) with configurable timeouts.

## Output

Returns step-by-step instructions including EIP-712 data to sign via Permit2, how to append the signature to the transaction, and how to broadcast it — plus code examples for executing the swap on Base chain via 0x.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "tokenIn": {
   "type": "string",
   "description": "Token to sell (symbol like USDC, WETH, VIRTUAL or 0x address)"
  },
  "amountIn": {
   "type": "string",
   "description": "Amount to swap in human-readable units (e.g. '0.1' for 0.1 WETH)"
  },
  "slippage": {
   "type": "string",
   "description": "Max slippage % (default: '1')"
  },
  "tokenOut": {
   "type": "string",
   "description": "Token to buy (symbol or 0x address)"
  },
  "walletAddress": {
   "type": "string",
   "description": "Your wallet address — you will sign the Permit2 data and submit the transaction"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/silverback-x402-onrender-com-d1e2ee4f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from silverback-x402.onrender.com](https://www.zero.xyz/host/silverback-x402.onrender.com/llms.txt)