Free Arbitrum One RPC Endpoint
Chain ID 42161 · ETH · multiple configured routing regions
Arbitrum One (Chain ID 42161) is Ethereum's leading optimistic rollup — full EVM equivalence and fast finality. NodeFlare serves Arbitrum RPC from nodes close to your users with automatic failover.
Public endpoint — no API key
HTTPS
https://rpc.nodeflare.app/arb/publicWSS
wss://rpc.nodeflare.app/arb/ws/publicNeed higher limits? Use a keyed endpoint https://rpc.nodeflare.app/arb/v1/{YOUR_KEY} — get a free key →
Connect to Arbitrum One
curl -s -X POST https://rpc.nodeflare.app/arb/public \
-H 'content-type: application/json' \
-d '{"jsonrpc":"2.0","id":1,"method":"eth_blockNumber","params":[]}'import { ethers } from "ethers";
const provider = new ethers.JsonRpcProvider(
"https://rpc.nodeflare.app/arb/public"
);
const block = await provider.getBlockNumber();import { createPublicClient, http } from "viem";
const client = createPublicClient({
transport: http("https://rpc.nodeflare.app/arb/public"),
});
const block = await client.getBlockNumber();from web3 import Web3
w3 = Web3(Web3.HTTPProvider(
"https://rpc.nodeflare.app/arb/public"
))
print(w3.eth.block_number)Add Arbitrum One to your wallet
Network details for MetaMask, Rabby, or any EVM wallet — Arbitrum One chain ID 42161 (0xa4b1).
| Network name | Arbitrum One |
| RPC URL | https://rpc.nodeflare.app/arb/public |
| Chain ID | 42161 |
| Currency symbol | ETH |
| Block explorer | https://arbiscan.io |
A wallet polls its RPC continuously. The keyless URL above allows 1 request per 10 seconds per IP: enough to confirm the network details, too low for daily wallet use. For a wallet, enter your keyed URL https://rpc.nodeflare.app/arb/v1/{YOUR_KEY} instead. A free key allows 10 requests per second, and the dashboard adds Arbitrum One to MetaMask with that URL in one click. Get a free key →
Built for Arbitrum One
Perps, DEXs, and capital-efficient DeFi on Arbitrum. Requests use configured regional preferences and available upstreams. Plan rate limits, compute units and method-specific concurrency limits apply.
Arbitrum One node coverage and routing
NodeFlare-operated primary nodes in 5 configured routing regions. A public third-party RPC backstop is configured after our own nodes. Region labels describe routing configuration rather than a guarantee that every gateway has a local node. A standard API key uses shared infrastructure with its own plan limits; dedicated capacity is scoped separately. Historical state, tracing and WebSocket support vary by chain and node.
On successful HTTP RPC responses, nf-region: fallback identifies an external backstop and nf-region: cache identifies a cached response. See our routing disclosure and availability terms.
Arbitrum One RPC — FAQ
What is Arbitrum One's chain ID?
Arbitrum One's chain ID is 42161 (hex 0xa4b1). Its native currency is ETH and its block explorer is arbiscan.io. You can connect with NodeFlare's free public RPC at https://rpc.nodeflare.app/arb/public — no API key required.
How do I add Arbitrum One to MetaMask?
In MetaMask, open the network menu → "Add a network" → "Add a network manually", then enter — Network name: Arbitrum One; Chain ID: 42161; Currency symbol: ETH; Block explorer URL: https://arbiscan.io; New RPC URL: your keyed NodeFlare URL, https://rpc.nodeflare.app/arb/v1/{YOUR_KEY}. A free key allows 10 requests per second. The keyless URL https://rpc.nodeflare.app/arb/public answers a test call, but it allows 1 request per 10 seconds per IP, which is too low for a wallet that polls the network continuously.
What is the Arbitrum One RPC URL?
NodeFlare's public Arbitrum One RPC URL is https://rpc.nodeflare.app/arb/public over HTTPS and wss://rpc.nodeflare.app/arb/ws/public over WSS. No API key is required for the public endpoint.
Is the Arbitrum One RPC free?
Yes. The public Arbitrum One endpoint is free with no sign-up. A free API key provides higher rate limits and 3,000,000 compute units per month, no credit card. Heavy HTTP methods depend on node support and are subject to compute-unit and concurrency limits.
What are the Arbitrum One RPC rate limits?
The public endpoint is limited to 1 request per 10 seconds per IP. A free key gives 10 requests/second; standard paid plans scale to 1500 req/s. Every plan includes all 17 supported chains.
Is NodeFlare a good Arbitrum One RPC provider?
NodeFlare operates its own primary Arbitrum One nodes. NodeFlare-operated primary nodes in 5 configured routing regions. A public third-party RPC backstop is configured after our own nodes. A free key provides 3,000,000 CU per month and higher limits. Method support and historical coverage depend on the node and requested block.
Is there a dedicated Arbitrum One RPC node?
A standard key gives an authenticated endpoint on shared NodeFlare infrastructure, with plan-specific limits. Dedicated capacity is scoped separately by inquiry. NodeFlare-operated primary nodes in 5 configured routing regions. A public third-party RPC backstop is configured after our own nodes. Historical state and traces must be checked for your specific methods and block ranges; a key does not guarantee complete archive coverage.
Go deeper
- Full Arbitrum One API reference → — supported methods, WebSocket, regions
- Rate limits & compute-unit costs → — what each method costs against your quota
- Pay per request with x402 → — Arbitrum One calls in USDC from $0.001, no account:
POST /arb/x402 - RPC for trading bots → and indexers → — low-latency, eth_getLogs-heavy workloads
- Screen a Arbitrum One token for scams → — ownership, honeypot check, holder concentration → one risk score
- Compare Arbitrum One gas prices → — live gas price and transaction cost next to the other chains, and a free token approval checker →
- Onchain tools for AI agents → — token-safety, wallet intelligence and RPC over MCP / x402
Build on Arbitrum One with a free key
Higher limits and an authenticated endpoint — every supported chain included. No credit card.
Get your free API key →Arbitrum One RPC methods
Per-method docs for Arbitrum One — parameters, compute-unit cost, and copy-paste examples.