# QuickNode JSON-RPC Proxy — zkSync Sepolia

> QuickNode JSON-RPC Proxy — zkSync Sepolia is a paid API for AI agents from x402.quicknode.com, paid per call via x402, $10/call, status unknown (last checked 2026-09-15).

Proxies JSON-RPC calls to the zkSync Sepolia testnet via QuickNode's infrastructure

## Facts

- Endpoint: POST https://x402.quicknode.com/zksync-sepolia/
- Price: $10/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quicknode-70781880
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cbxP0Fn42wwwkfuTAYNyI

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 quicknode-70781880 -d '<json body>'
```

Example prompt: Call eth_getBalance on zkSync Sepolia testnet for address 0xAbCd...1234 using QuickNode's RPC endpoint — I want to check how much ETH is in that wallet.

## When to prefer this

Use this endpoint when you need to interact with the zkSync Sepolia testnet specifically — for testing zkSync Era Layer 2 smart contracts, checking testnet balances, or validating transactions before mainnet deployment. Prefer this over generic Ethereum RPC endpoints when the target chain is zkSync Sepolia (chain ID 300).

## Known failure modes

- Invalid JSON-RPC method name returns error code -32601 (method not found)
- Malformed params array returns error code -32602 (invalid params)
- Network or node unavailability returns HTTP 503 or JSON-RPC error
- Insufficient payment (x402 payment not attached) returns HTTP 402
- Rate limiting or quota exceeded returns HTTP 429
- Contract revert returns execution reverted error in result

## How this service works

JSON-RPC proxy — zksync-sepolia

## Output

Returns a standard JSON-RPC 2.0 response object containing the result of the requested method (e.g. block data, balance in hex wei, transaction receipt, call return value) or an error object with code and message if the call fails.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "jsonrpc",
  "method"
 ],
 "properties": {
  "id": {
   "type": [
    "number",
    "string"
   ],
   "description": "Request identifier"
  },
  "method": {
   "type": "string",
   "description": "JSON-RPC method name (e.g., eth_blockNumber, eth_call)"
  },
  "params": {
   "type": "array",
   "description": "Method parameters"
  },
  "jsonrpc": {
   "type": "string",
   "const": "2.0"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "id": {
   "type": [
    "number",
    "string"
   ]
  },
  "error": {
   "type": "object",
   "properties": {
    "code": {
     "type": "integer"
    },
    "message": {
     "type": "string"
    }
   }
  },
  "result": {
   "description": "RPC result (type varies by method)"
  },
  "jsonrpc": {
   "type": "string",
   "const": "2.0"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quicknode-70781880/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.quicknode.com](https://www.zero.xyz/host/x402.quicknode.com/llms.txt)