Free Arbitrum RPC Endpoint — No API Key Required

Arbitrum One is Ethereum's leading optimistic rollup — lower fees, faster finality, and full EVM equivalence. Whether you're deploying contracts, running an indexer, or building a DeFi protocol, you need a reliable RPC endpoint.

NodeFlare provides free, multi-region Arbitrum RPC nodes. The public endpoint works without a key; a free account unlocks higher rate limits and heavy method support (eth_getLogs, trace_*, debug_*) — all on the free tier.

Arbitrum RPC Endpoint#

Public endpoint — no API key required:

https://rpc.nodeflare.app/arb/public
wss://rpc.nodeflare.app/arb/ws/public

Keyed endpoint (free account — higher limits):

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

Get your free key →

Quick Start#

curl#

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

ethers.js#

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider(
  'https://rpc.nodeflare.app/arb/public'
);

const block = await provider.getBlockNumber();
console.log('Latest Arbitrum block:', block);

viem#

import { createPublicClient, http } from 'viem';
import { arbitrum } from 'viem/chains';

const client = createPublicClient({
  chain: arbitrum,
  transport: http('https://rpc.nodeflare.app/arb/public'),
});

const block = await client.getBlockNumber();

Arbitrum One at a Glance#

Arbitrum One uses a fraud-proof rollup architecture: transactions execute off-chain, but data is posted to Ethereum L1 so anyone can verify and challenge invalid state transitions. This gives you Ethereum-grade security at a fraction of the cost.

Free Tier Details#

NodeFlare's free tier gives you:

• 2,000,000 compute units per month — no credit card required
• eth_getLogs, trace_*, debug_* — heavy methods included on free
• WebSocket (wss://) — same endpoint, same monthly allowance
• 5+ global regions — geo-routed requests with automatic failover
• All 23 supported EVM chains under one key: Arbitrum, Base, Ethereum, Optimism, Avalanche, BNB Chain, HyperEVM and more

Compute units are consumed per call based on method complexity. eth_blockNumber costs 1 CU; eth_getLogs costs 75 CU; trace_* and debug_* cost 100 CU each. The rate limits page has the full table.

Why NodeFlare for Arbitrum?#

Most free RPC providers throttle or block heavy methods. Fetching event logs across a large block range with eth_getLogs, running debug_traceTransaction to decode a failed tx, or streaming new blocks over WebSocket — these are exactly the calls that get rate-limited or rejected on shared free tiers.

NodeFlare runs its own bare-metal nodes — no third-party aggregation. That means heavy methods work on the free tier, there are no surprise cold-start delays, and you're not sharing capacity with thousands of anonymous users on the same IP range.

Using eth_getLogs on Arbitrum#

eth_getLogs is the workhorse for indexing contract events. Here's an example fetching Transfer events from a token contract:

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider(
  'https://rpc.nodeflare.app/arb/v1/{YOUR_KEY}'
);

const logs = await provider.getLogs({
  address: '0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC1', // USDC.e (bridged) on Arbitrum
  topics: [ethers.id('Transfer(address,address,uint256)')],
  fromBlock: 'latest',
  toBlock: 'latest',
});

console.log(`${logs.length} Transfer events in the latest block`);

For historical ranges, replace fromBlock/toBlock with specific block numbers. The free tier supports wide ranges; see rate limits for per-method compute unit costs.

Adding Arbitrum to MetaMask#

1. Open MetaMask → Settings → Networks → Add Network
2. RPC URL: https://rpc.nodeflare.app/arb/public
3. Chain ID: 42161
4. Currency Symbol: ETH
5. Block Explorer: https://arbiscan.io

Save and switch to Arbitrum One. The public endpoint is rate-limited per IP; sign up for a free key for a dedicated path with higher limits.

Frequently Asked Questions#

What is the Arbitrum One RPC URL?
https://rpc.nodeflare.app/arb/public (HTTPS) and wss://rpc.nodeflare.app/arb/ws/public (WebSocket). No API key required for the public endpoint.

Is the Arbitrum RPC free?
Yes. The public endpoint is free with no sign-up (rate-limited per IP). A free account gives 2,000,000 compute units per month and a dedicated keyed path — no credit card.

Does NodeFlare support eth_getLogs on Arbitrum?
Yes. eth_getLogs, trace_block, debug_traceTransaction, and other heavy methods all work on the free tier.

What is Arbitrum One's Chain ID?
42161. Arbitrum Nova (a separate, AnyTrust chain) uses Chain ID 42170 — make sure you're using the right one.

What's the difference between the public and keyed endpoint?
The public endpoint is shared, rate-limited to 2 req/s per IP. The keyed endpoint (/arb/v1/{YOUR_KEY}) is dedicated, starts at 10 req/s on the free plan, and includes all heavy methods. Both are free; the keyed path just requires a free account.

Ready to build on Arbitrum? Get your free NodeFlare key → — covers Arbitrum plus all 23 supported chains, no credit card required.