# QuickNode JSON-RPC Proxy — Ethereum Sepolia

> QuickNode JSON-RPC Proxy — Ethereum Sepolia is a paid API for AI agents from x402.quicknode.com, paid per call via x402, $10/call, status unknown (last checked 2026-09-14).

Proxies JSON-RPC calls to the Ethereum Sepolia testnet, enabling blockchain queries and interactions via standard Ethereum JSON-RPC methods.

## Facts

- Endpoint: POST https://x402.quicknode.com/ethereum-sepolia/
- Price: $10/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quicknode-5d8ded40
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Bzf0fzQ9OjVvusCbcfcWX

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-5d8ded40 -d '<json body>'
```

Example prompt: Using QuickNode's Ethereum Sepolia RPC, call eth_getBalance for address 0xAbC123... on Sepolia testnet to check how much ETH it holds.

## When to prefer this

Use this endpoint when you need to interact with the Ethereum Sepolia testnet specifically — for testing smart contracts, verifying testnet transactions, or developing dApps without spending real ETH. Prefer this over mainnet endpoints during development and testing phases. QuickNode's infrastructure offers reliable, low-latency RPC access compared to public free endpoints.

## Known failure modes

- Invalid JSON-RPC method name returns error code -32601 Method not found
- Malformed params array returns error code -32602 Invalid params
- Payment not provided or invalid returns HTTP 402 Payment Required
- Network congestion may cause timeouts
- Calling mainnet-only methods on Sepolia may return unexpected results or errors
- Requesting non-existent transaction hashes returns null result

## How this service works

JSON-RPC proxy — ethereum-sepolia

## Output

Returns a standard JSON-RPC 2.0 response object containing the result of the requested method (e.g. block number as hex, balance in wei, transaction receipt object, contract return data), 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-5d8ded40/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)