Quick Start

TheRPC is a managed JSON-RPC provider that gives you fast, authenticated access to Arbitrum One without running your own Nitro node. Developers building on Arbitrum One — DeFi front ends for GMX or Camelot, wallets, indexers, trading backends — use it for low-latency reads against the sequencer and reliable transaction submission on chain ID 42161. This guide takes you from zero to a working JSON-RPC call in a few minutes, with examples in curl, JavaScript, and Python.

Step 1: Get an API Key

Sign up for a free account at TheRPC.io, then open the Dashboard and head to the API Keys section to create a new key or copy an existing one. The key is a secret token you pass on every request; in this guide it stands in for the YOUR_API_KEY placeholder in the Arbitrum One endpoint https://arbitrum.therpc.io/YOUR_API_KEY.

Step 2: Choose Your Network

TheRPC serves many networks, each on its own endpoint host. For Arbitrum One, point your client at https://arbitrum.therpc.io/YOUR_API_KEY. Set the endpoint URL and your API key as environment values, as shown below, so the rest of your code stays clean and you can swap networks later by changing a single variable.

Step 2: Choose Your Network

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

Step 3: Make Your First Call

Now make your first call to Arbitrum One. The three snippets below — curl, JavaScript, and Python — all run the same eth_blockNumber request and return the latest block height. Pick whichever matches your stack; for broader language coverage, see the full Tools & SDKs reference.

Using Curl

1curl --request POST https://arbitrum.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://arbitrum.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://arbitrum.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 beat raw HTTP calls: they handle ABI encoding and decoding, transaction signing, gas estimation that accounts for Arbitrum One's combined L2-plus-L1 fee model, and nonce management for you. Because Arbitrum One is Ethereum-equivalent, standard libraries work unchanged. See the Tools & SDKs documentation for full language-specific coverage.

Web3.js (JavaScript)

1const Web3 = require('web3');
2const web3 = new Web3('https://arbitrum.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://arbitrum.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 All Methods page is the complete reference for every JSON-RPC method available on Arbitrum One through TheRPC. Each entry includes a description, the request and response formats, copy-paste code examples, and typical use cases, organized by namespace so you can quickly find the eth_, debug_, trace_, or utility method you need.

Network Selection

Each network TheRPC supports has its own dedicated endpoint. For Arbitrum One the URL is https://arbitrum.therpc.io/YOUR_API_KEY — keep it in configuration so switching to or from another network is a one-line change.

Next Steps

• All Methods — browse the full Arbitrum One JSON-RPC method reference
• Tools & SDKs — set up your language's library against chain 42161
• Authentication — secure your API key and Bearer header
• Rate Limits — understand quotas and retry strategies
• Basic Operations — work through balances, transactions, blocks, and contract calls