Quick Start

TheRPC is a managed JSON-RPC provider that gives you fast, authenticated access to OP Mainnet without running your own OP Stack node. Developers building on the Superchain — from Velodrome and Synthetix integrations to indexers and wallets — use it for reliable reads and transaction broadcasting against chain ID 10. This guide takes you from zero to a working call in a few minutes: grab an API key, point your client at the OP Mainnet endpoint, and run your first request in curl, JavaScript, or Python.

Step 1: Get an API Key

Sign up for a free account at TheRPC.io, then open the Dashboard and go to the API Keys section to create a new key or retrieve an existing one. The key is a single secret string; you'll place it in the OP Mainnet endpoint URL (https://optimism.therpc.io/YOUR_API_KEY) and in the Authorization: Bearer header on every request.

Step 2: Choose Your Network

TheRPC serves many networks from a single account, each at its own endpoint host. To target OP Mainnet, set your environment to the OP Mainnet endpoint URL with your API key, as shown below. The same key works across every network you have access to — only the host changes.

Step 2: Choose Your Network

1API_ENDPOINT="https://optimism.therpc.io/YOUR_API_KEY"
2API_KEY="YOUR_API_KEY"

Step 3: Make Your First Call

Now make your first OP Mainnet call. The examples below show the same eth_blockNumber request three ways — curl, JavaScript, and Python — so you can pick whichever fits your stack. For more languages and full client setup, see the Tools & SDKs reference.

Using Curl

1curl --request POST https://optimism.therpc.io/YOUR_API_KEY \
2  --header 'Content-Type: application/json' \
3  --header 'Authorization: Bearer YOUR_API_KEY' \
4  --data '{
5    "jsonrpc": "2.0",
6    "method": "eth_blockNumber",
7    "params": [],
8    "id": 1
9  }'

Using JavaScript

1const axios = require('axios');
2 
3const config = {
4  url: 'https://optimism.therpc.io/YOUR_API_KEY',
5  apiKey: 'YOUR_API_KEY',
6};
7 
8async function getBlockNumber() {
9  const response = await axios.post(
10    config.url,
11    {
12      jsonrpc: '2.0',
13      method: 'eth_blockNumber',
14      params: [],
15      id: 1,
16    },
17    {
18      headers: {
19        'Content-Type': 'application/json',
20        Authorization: `Bearer ${config.apiKey}`,
21      },
22    },
23  );
24 
25  console.log('Latest Block Number:', response.data.result);
26}

Using Python

1import requests
2 
3config = {
4    'url': 'https://optimism.therpc.io/YOUR_API_KEY',
5    'api_key': 'YOUR_API_KEY'
6}
7 
8def get_block_number():
9    response = requests.post(
10        config['url'],
11        headers={
12            'Content-Type': 'application/json',
13            'Authorization': f"Bearer {config['api_key']}"
14        },
15        json={
16            'jsonrpc': '2.0',
17            'method': 'eth_blockNumber',
18            'params': [],
19            'id': 1
20        }
21    )
22    return response.json()['result']

Step 4: Using Web3 Libraries

For anything beyond a single read, Web3 libraries are easier than hand-built HTTP calls: they handle ABI encoding, unit conversion, transaction signing, and retries for you, so reading a Velodrome pool or sending an ETH transfer on OP Mainnet becomes a few lines. The examples below wire web3.js and web3.py to the OP Mainnet endpoint; see the Tools & SDKs documentation for full, language-specific coverage.

Web3.js (JavaScript)

1const Web3 = require('web3');
2const web3 = new Web3('https://optimism.therpc.io/YOUR_API_KEY');
3 
4// Add API key to requests
5web3.setHeader('Authorization', 'Bearer YOUR_API_KEY');
6 
7async function getBalance(address) {
8  const balance = await web3.eth.getBalance(address);
9  return web3.utils.fromWei(balance, 'ether');
10}

Web3.py (Python)

1from web3 import Web3
2from web3.middleware import http_retry_request_middleware
3 
4w3 = Web3(Web3.HTTPProvider(
5    'https://optimism.therpc.io/YOUR_API_KEY',
6    request_kwargs={
7        'headers': {'Authorization': 'Bearer YOUR_API_KEY'}
8    }
9))
10 
11# Add retry middleware
12w3.middleware_onion.add(http_retry_request_middleware)

Available Methods

The full list of methods TheRPC supports on OP Mainnet lives on the All Methods page, organized by namespace. Each method's reference includes a plain-English description, request and response formats, copy-paste code examples, and typical use cases — so you can move from this quick start to building real features quickly.

Network Selection

Each network TheRPC serves has its own endpoint host, so you select a chain simply by choosing its URL. For OP Mainnet the endpoint is https://optimism.therpc.io/YOUR_API_KEY over HTTP, with wss://optimism.therpc.io/YOUR_API_KEY for WebSocket subscriptions.

Next Steps

• All Methods — browse every JSON-RPC method available on OP Mainnet.
• Tools & SDKs — set up the client library for your language.
• Authentication — learn how to manage and secure your API key.
• Rate Limits — understand quotas and how to handle them gracefully.
• Basic Operations — work through the most common OP Mainnet reads and writes.