How to add a private RPC to MetaMask for Ethereum (and make sure it's used)

Changing the RPC is the single setting that keeps your Ethereum swaps out of the public mempool. It takes a minute, but there is one step that is easy to miss.

Step 1. Add the network RPC

Go to backrun.io, choose the Ethereum tab and press Add to wallet in the RPC section, then approve the request in MetaMask. Or add it by hand in MetaMask's network settings:

• Network name: backrun · Ethereum
• RPC URL: https://eth.backrun.io
• Chain ID: 1
• Currency: ETH
• Block explorer: https://etherscan.io

Step 2. Select it as the RPC for Ethereum

This is the step most people miss. MetaMask already knows Ethereum, so adding a new RPC puts it in the list but keeps the old default. Until you switch, your transactions still go out through the old RPC.

1. Open MetaMask's menu, then Settings → Networks (or the network list).
2. Under Ethereum, tap the RPC name shown below it (for example mainnet.infura.io).
3. Choose backrun · Ethereum. The line under Ethereum should now say backrun.

Step 3. Confirm it works

Go back to backrun.io, choose the Ethereum tab and press Check my wallet. It asks your wallet a question only the backrun RPC answers, so a check mark means your Ethereum transactions are going through backrun.

About the MetaMask warning

When adding the RPC, MetaMask may say the RPC URL does not match a known provider for this chain ID. That means the URL is not on the public list MetaMask uses for well-known providers yet; it is not a sign that something is wrong with the network. Always check that the URL is exactly https://eth.backrun.io before approving.

MetaMask Smart Transactions

MetaMask has its own protection feature, Smart Transactions. According to MetaMask's documentation, a custom RPC set in your network settings overrides Smart Transactions, so once backrun is selected your Ethereum transactions go through backrun.

Other wallets

Most wallets that allow a custom RPC work the same way: add the RPC URL for chain ID 1, then make sure it is the one selected for Ethereum. Wallets that do not let you change the RPC send transactions through their own servers.