# QuickNode JSON-RPC Proxy — Base Sepolia

> QuickNode JSON-RPC Proxy — Base 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 requests to the Base Sepolia testnet, enabling Ethereum-compatible blockchain queries and interactions on the Base L2 test network.

## Facts

- Endpoint: POST https://x402.quicknode.com/base-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-1f34df38
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0_-LQINQvtCV6d8-5OoDe

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-1f34df38 -d '<json body>'
```

Example prompt: Call eth_getBalance on Base Sepolia testnet for address 0xAbC123... at the latest block — use the QuickNode JSON-RPC proxy.

## When to prefer this

Use this endpoint when you need to interact with the Base Sepolia testnet specifically — ideal for testing Base L2 smart contracts, simulating transactions, or querying testnet state without spending real funds. Prefer this over mainnet endpoints when doing development or QA on Base.

## Known failure modes

- Invalid JSON-RPC method name returns error code -32601
- Malformed params array returns error code -32602
- Payment not received or insufficient USDC results in 402 Payment Required
- Network unavailable or node sync issues return 503 or timeout
- Unsupported method for Base Sepolia returns error

## How this service works

JSON-RPC proxy — base-sepolia

## Output

Returns a standard JSON-RPC 2.0 response object containing the result of the requested method (e.g. block data, balance in wei, transaction receipt, contract return value) or an error object 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-1f34df38/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)