# QuickNode JSON-RPC Proxy — Optimism Sepolia

> QuickNode JSON-RPC Proxy — Optimism 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 Optimism Sepolia testnet blockchain via QuickNode's infrastructure

## Facts

- Endpoint: POST https://x402.quicknode.com/optimism-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-68d693f3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MMLfC9hCJfRiaetoY17p9

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-68d693f3 -d '<json body>'
```

Example prompt: Call eth_getBalance on Optimism Sepolia testnet for address 0xAbC...123 — use the QuickNode JSON-RPC proxy to get the current balance in wei.

## When to prefer this

Use this endpoint when you need to interact with the Optimism Sepolia testnet specifically — ideal for testing smart contracts, checking testnet balances, or developing Optimism Layer 2 applications before mainnet deployment. Prefer this over Ethereum Sepolia when targeting OP Stack contracts or Optimism-specific RPC methods.

## 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 unavailable or node down returns HTTP 503
- Payment not included or insufficient returns HTTP 402
- Rate limit exceeded returns HTTP 429
- Contract call reverts returns execution error in result field

## How this service works

JSON-RPC proxy — optimism-sepolia

## Output

Returns a standard JSON-RPC 2.0 response object containing the result of the requested blockchain method — e.g. block number as a hex string, account balance in wei, transaction receipt object, or smart contract return data — along with the original request ID and jsonrpc version field.

## 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-68d693f3/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)