How to Add a Custom RPC Endpoint to MetaMask

MetaMask ships with built-in RPC endpoints for the major networks, but you can replace them with a faster, more reliable provider in about 30 seconds. Here's exactly how — with copy-paste URLs for the seven most-used of the 23 chains NodeFlare serves — the same pattern works for every chain: swap the chain slug.

Why add a custom RPC?#

The defaults MetaMask ships with are shared public infrastructure — busy, rate-limited, and sometimes slow at peak hours. A dedicated RPC gives you:

• Lower latency — nodes geographically close to you, not a congested shared pool
• Higher rate limits — your own key means your traffic is isolated from other users
• Reliability — automatic failover between nodes so you're not waiting on a hung endpoint

How to add a network in MetaMask#

1. Open MetaMask and click the network selector at the top-left (shows the current network name).
2. Click Add network.
3. Click Add a network manually at the bottom of the list.
4. Fill in the fields from the tables below for the chain you want.
5. Click Save.

MetaMask will switch to the new network immediately.

To update an existing network's RPC (for example, to replace the default Ethereum endpoint):

1. Network selector → ⋮ next to the network → Edit.
2. Change New RPC URL to the NodeFlare endpoint below.
3. Save.

NodeFlare endpoints for MetaMask#

All public endpoints below work without an API key. For higher rate limits and access to heavy methods (eth_getLogs, trace_*, debug_*), sign up for a free key (no credit card) and swap /public for /v1/YOUR_KEY.

Ethereum Mainnet#

Full Ethereum RPC reference →

Base#

Full Base RPC reference →

Arbitrum One#

Full Arbitrum RPC reference →

Optimism#

Full Optimism RPC reference →

BNB Smart Chain#

Full BNB Chain RPC reference →

HyperEVM (Hyperliquid)#

Full HyperEVM RPC reference →

Avalanche C-Chain#

Full Avalanche RPC reference →

Use a keyed endpoint for higher limits#

The public endpoints are rate-limited per IP — fine for testing, not for sustained use. A free NodeFlare API key gives you:

• 2,000,000 compute units/month — no credit card
• A dedicated path isolated from public traffic
• Heavy methods — eth_getLogs, trace_*, debug_* — all free

The endpoint format with a key:

https://rpc.nodeflare.app/{chain}/v1/YOUR_KEY

For example, Ethereum with a key: https://rpc.nodeflare.app/eth/v1/YOUR_KEY

To get your key: visit nodeflare.app, sign up, and copy the key from the dashboard. Swap the URL in MetaMask — nothing else changes.

Troubleshooting#

"Could not fetch chain ID" — Check the RPC URL for typos. The chain slug must be exact: eth, base, bnb, arb, op, hl, or avax.

"Chain ID does not match" — Make sure the Chain ID field matches exactly. Common mistake: confusing Arbitrum One (42161) with Arbitrum Sepolia (421614).

Transactions slow or failing — The public endpoint shares capacity. Switch to a free API key for a dedicated path. See the rate limits reference for per-method compute unit weights.

What's next#

Once the network is added in MetaMask, the same endpoint works in code — paste the URL into an ethers.js JsonRpcProvider, a viem http() transport, or a web3.py HTTPProvider. One key, every chain, the same URL format.

• Quick-start guide — first request in 60 seconds
• Endpoint reference — full list of supported JSON-RPC methods
• Rate limits — compute unit weights by method
• Pricing — free plan details and paid tiers