What is an Arbitrum RPC node and how do you choose the right one?

Arbitrum RPC Node Decision Checklist

Before you pick an Arbitrum RPC provider, evaluate these criteria:

What Is an Arbitrum RPC Node?

An Arbitrum RPC (Remote Procedure Call) node is a server that exposes the Arbitrum blockchain's API. Your wallet, dApp, or backend sends JSON-RPC requests to this endpoint to query balances, send transactions, or call smart contracts. Arbitrum is an Ethereum Layer 2 scaling solution that uses optimistic rollups. It has two main networks:

• Arbitrum One (Chain ID 42161) – the production mainnet.
• Arbitrum Nova (Chain ID 42170) – a low-cost AnyTrust chain for gaming and social apps.
• Arbitrum Sepolia (Chain ID 421614) – the testnet for development.

Chain Settings and Public Endpoints

Arbitrum provides official public RPC endpoints, but they are rate-limited and not suitable for production. Here are the official endpoints:

These public endpoints do not support WebSocket. For real-time subscriptions, you need a third-party provider that offers WSS.

How to Connect to an Arbitrum RPC Node

You can test an Arbitrum RPC endpoint with a simple curl command:

curl -X POST https://arb1.arbitrum.io/rpc \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Expected response:

{"jsonrpc":"2.0","id":1,"result":"0x1d0f3a2"}

In JavaScript (ethers.js):

const { ethers } = require("ethers");
const provider = new ethers.JsonRpcProvider("https://arb1.arbitrum.io/rpc");
provider.getBlockNumber().then(console.log);

Public vs. Private RPC Nodes

Public (Shared) Endpoints

• Free to use but often rate-limited (e.g., 10–100 req/s).
• No SLA; may go down without notice.
• Suitable for development, testing, and low-traffic apps.

Private (Dedicated) Endpoints

• Higher rate limits or unlimited requests.
• Dedicated node resources for consistent performance.
• Often include archive data, WebSocket, and trace APIs.
• Backed by SLAs and support.

For production dApps, a managed RPC service like OnFinality provides dedicated Arbitrum nodes with configurable throughput, archive access, and multi-region failover. Check the Arbitrum network page for available endpoints.

When to Use a Dedicated Arbitrum Node

Consider a dedicated node if your application:

• Processes more than 100 requests per second.
• Requires archive data for historical queries.
• Needs WebSocket subscriptions for real-time data.
• Demands high availability with automatic failover.
• Runs trading bots, analytics pipelines, or high-frequency transaction systems.

OnFinality's dedicated node offering gives you a private Arbitrum endpoint with no shared rate limits. You can also combine it with our RPC API service for additional features like caching and load balancing.

Common Pitfalls and Troubleshooting

Rate Limiting

Public endpoints return 429 Too Many Requests when overloaded. Switch to a provider with higher limits or a dedicated node.

Sequencer vs. Regular Endpoint

Arbitrum has a sequencer endpoint that accepts transactions and includes them faster. The official sequencer URL for Arbitrum One is https://arb1-sequencer.arbitrum.io/rpc. However, it only supports eth_sendRawTransaction and eth_sendRawTransactionConditional. For all other RPC methods, use the regular endpoint.

WebSocket Not Supported on Public Endpoints

If your dApp needs real-time updates, you must use a third-party provider that offers WSS. OnFinality supports WebSocket for Arbitrum networks.

Archive Data

By default, full nodes only keep recent state. For historical eth_call or eth_getBalance at old blocks, you need an archive node. Most managed providers offer archive access on paid tiers.

How to Choose an Arbitrum RPC Provider

When evaluating providers, compare:

1. Network coverage – Do they support Arbitrum One, Nova, and Sepolia?
2. Throughput – What is the RPS limit? Is it burstable?
3. Archive support – Is archive data available? At what cost?
4. WebSocket – Is WSS available? Any connection limits?
5. Geographic distribution – Are endpoints available in multiple regions?
6. Pricing – Is it pay-per-request, flat monthly, or dedicated node?
7. Support – Is there a free tier? What is the SLA?

For a full list of supported networks, see our networks page. For pricing details, visit RPC pricing.

Key Takeaways

• An Arbitrum RPC node is the gateway to interact with Arbitrum One, Nova, and Sepolia.
• Public endpoints are free but limited; production apps need a managed provider.
• Evaluate rate limits, archive data, WebSocket, and failover when choosing a provider.
• Dedicated nodes offer consistent performance and are ideal for high-traffic dApps.
• Always test with a simple curl or ethers.js script before integrating.

Frequently Asked Questions

What is the difference between Arbitrum One and Arbitrum Nova?

Arbitrum One is the main rollup for general DeFi and dApps. Arbitrum Nova is an AnyTrust chain optimized for low-cost transactions, ideal for gaming and social applications.

Can I use the same RPC endpoint for Arbitrum One and Nova?

No. Each network has its own chain ID and RPC URL. You must configure your dApp to point to the correct endpoint.

Do I need an archive node for my dApp?

Only if your dApp queries historical state (e.g., past balances, events). Most dApps can work with a full node.

How do I get a WebSocket endpoint for Arbitrum?

Public endpoints do not support WebSocket. Use a third-party provider like OnFinality that offers WSS.

What is the Arbitrum sequencer endpoint?

It's a special endpoint that accepts transactions and includes them faster. It only supports eth_sendRawTransaction and eth_sendRawTransactionConditional.

Is OnFinality compatible with Arbitrum?

Yes. OnFinality provides RPC endpoints and dedicated nodes for Arbitrum One, Nova, and Sepolia. Visit the Arbitrum network page for details.