How to Set a Custom RPC for Arbitrum in MetaMask

02 November 2026

To add Arbitrum One or Arbitrum Nova to MetaMask, you enter the network's RPC details manually in MetaMask's network settings. This page walks through the procedure step by step, including where to find current RPC endpoints and what each field means.

Why Add a Custom RPC Instead of Using Chainlist

MetaMask ships with Ethereum mainnet and a few testnets pre-configured. Arbitrum is not one of them. You can use a service like Chainlist to add it in one click, but adding manually gives you control over which RPC provider you use. That matters because public RPC endpoints can become rate-limited or slow during congestion.

What you need before starting

• MetaMask installed and set up, with at least one wallet imported or created.
• An RPC endpoint URL for the Arbitrum chain you want. The official Arbitrum documentation lists current public endpoints. You can also use a provider such as Alchemy, Infura, or QuickNode - each offers free-tier Arbitrum endpoints with higher rate limits than the public ones.
• The chain ID for Arbitrum One is 42161. For Arbitrum Nova it is 42170.
• The native token symbol is ETH on both chains (Arbitrum uses wrapped ETH as its gas token).
• The block explorer URL for Arbitrum One is arbiscan.io; for Nova it is nova.arbiscan.io.

Step-by-Step: adding arbitrum one to metamask

1. Open MetaMask and click the network dropdown at the top of the extension window. It usually shows "Ethereum Mainnet" by default.
2. Click "Add Network" at the bottom of the dropdown menu. MetaMask will open a new tab in your browser with the network settings form.
3. Fill in the fields:
4. Network Name: Type "Arbitrum One" (or any label you prefer).
5. New RPC URL: Paste your chosen RPC endpoint. A public example is https://arb1.arbitrum.io/rpc. If you use a provider, the URL will look different - Alchemy's might be https://arb-mainnet.g.alchemy.com/v2/YOUR_API_KEY.
6. Chain ID: Enter 42161.
7. Currency Symbol: Enter ETH.
8. Block Explorer URL: Enter https://arbiscan.io.
9. Click "Save". MetaMask will switch to the new network and show an ETH balance of zero until you bridge funds.

Repeating for arbitrum nova

The process is identical except for three values:

• RPC URL: Public endpoint is https://nova.arbitrum.io/rpc. Provider-specific URLs differ.
• Chain ID: 42170.
• Block Explorer URL: https://nova.arbiscan.io.

You can add both chains. MetaMask will remember them and let you switch between networks via the dropdown.

Testing the Connection

After saving, MetaMask attempts to fetch your balance. If the network name appears in the dropdown and the balance field does not show an error, the connection works. To confirm, try sending a small amount of ETH to another Arbitrum address you control. If the transaction goes through and appears on Arbiscan, the RPC is functioning.

If MetaMask shows "Could not fetch chain ID" or a similar error, double-check the RPC URL and chain ID. A typo in either field will break the connection. Also verify that your chosen RPC endpoint is currently online - public endpoints can occasionally go down. If one fails, try another from the list in Arbitrum's documentation.

Choosing an RPC provider

The public endpoint at arb1.arbitrum.io/rpc is free and open, but it has no guaranteed rate limit. Heavy users may hit request caps. For frequent trading or automated scripts, a paid provider like Alchemy, Infura, or QuickNode offers dedicated endpoints with higher limits and often lower latency.

Each provider has its own signup process and API key. You paste that key into the RPC URL. For example, with Infura you create a project, select Arbitrum as the network, and copy the provided endpoint URL into MetaMask. The free tier of most services is sufficient for occasional use.

What can go wrong

• Wrong chain ID: Entering 42170 for Arbitrum One will connect to Nova instead. Transactions will fail or route incorrectly.
• Outdated RPC URL: Providers occasionally deprecate old endpoints. Check the provider's documentation if your connection stops working.
• Rate limiting: Public endpoints may reject repeated requests. If MetaMask struggles to load your balance or transactions, switch to a provider endpoint.
• MetaMask cache: If you change RPC URLs for an existing network, MetaMask sometimes holds stale data. Removing the network and re-adding it with the new URL clears the cache.

Removing or Editing a Custom Network

To edit or delete a custom Arbitrum network, go to MetaMask's settings (click the circle icon in the top right, then "Settings"), select "Networks", find the Arbitrum entry, and click the three dots on the right. You can edit the details or delete the network entirely. Deleting does not affect your funds - they remain on the chain, accessible by re-adding the network later.

Once the custom RPC is set and working, you can bridge ETH onto Arbitrum using the official Arbitrum bridge or a third-party bridge, then use any dApp on the chain directly from MetaMask.

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