# QuickNode JSON-RPC Proxy — B3 Mainnet

> QuickNode JSON-RPC Proxy — B3 Mainnet 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 B3 mainnet blockchain network via QuickNode's infrastructure

## Facts

- Endpoint: POST https://x402.quicknode.com/b3-mainnet/
- 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-37ce4eef
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Y_R3h9pyZrF2HXWk7p7yj

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-37ce4eef -d '<json body>'
```

Example prompt: Can you call eth_blockNumber on B3 mainnet to get the latest block height?

## When to prefer this

Use this endpoint when you need direct JSON-RPC access to the B3 mainnet blockchain — for reading on-chain state, querying blocks or transactions, calling smart contracts, or broadcasting transactions on B3. Prefer this over generic alternatives when you specifically need B3 mainnet (not testnet) and want QuickNode's reliable node infrastructure.

## Known failure modes

- Invalid JSON-RPC method name returns error object with code and message
- Malformed params array causes parse or invalid params error
- Payment failure (insufficient USDC) results in 402 Payment Required
- Network congestion or node unavailability may cause timeout or 503
- Unsupported method for B3 network returns method not found error

## How this service works

JSON-RPC proxy — b3-mainnet

## Output

Returns a standard JSON-RPC 2.0 response object containing the result of the requested method (e.g. block number, transaction data, contract return value) or an error object if the call failed.

## 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-37ce4eef/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)