Nitro · Sequencer-first UX

Arbitrum One RPC

rpcfree.com provides a free public JSON-RPC endpoint for Arbitrum One (chain ID 42161). No signup, no API key required. 333,000 calls per day. Supports archive data, trace methods, and is compatible with MetaMask, ethers.js, viem, and hardhat.

HTTPS endpoint LIVE

https://rpcfree.com/arbitrum-rpc

Chain ID 42161 (0xa4b1) · Currency ETH · Sequencer confirmation ~250ms · L1 challenge window ~7 days (canonical bridge)

Arbitrum docs Try in browser

Live from this RPC

Values refresh every 12 seconds via public dRPC while rpcfree RPC is paused. Gas is shown in Gwei (wei ÷ 10⁹).

Latest block —

Suggested gas price —

Round-trip latency —

Quick start with viem

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

const client = createPublicClient({
  chain: arbitrum,
  transport: http("https://rpcfree.com/arbitrum-rpc")
});

const block = await client.getBlockNumber(); // L2 height from RPC

const l2FromPrecompile = await client.readContract({
  address: "0x0000000000000000000000000000000000000064",
  abi: [
    { name: "arbBlockNumber", type: "function", stateMutability: "view", inputs: [], outputs: [{ type: "uint256" }] }
  ],
  functionName: "arbBlockNumber"
});

The L1 / L2 block number quirk

Off-chain: eth_blockNumber returns the L2 sequencer height — what you expect in dashboards.

On-chain: Solidity’s block.number returns the approximate Ethereum L1 block number, not the L2 height. This preserves time-correlated assumptions for contracts written with ~12s Ethereum cadence in mind.

// Inside a contract on Arbitrum:
uint256 l1ish = block.number; // L1-aligned
// For true L2 height from contracts, call ArbSys (address 100):
IArbSys(0x0000000000000000000000000000000000000064).arbBlockNumber();

When it bites you

Time-locks keyed to “wait N blocks”.
Snapshot voting that stores block.number.
Indexers mixing RPC block heights with on-chain values.

Mitigation: treat block.number as L1-correlated time, and call ArbSys when you explicitly need the L2 sequencer height inside the VM.

Arbitrum One vs Arbitrum Nova

	Arbitrum One (this RPC)	Arbitrum Nova
Chain ID	42161	42170
Data availability	L1 (calldata / blobs)	DAC (committee)
Security model	Full rollup	AnyTrust
Cost	Low (~$0.01–0.10 typical)	Very low (~$0.001)
Common use	DeFi, general finance	Gaming, social

Deploying financial logic → stay on One. Ultra-high throughput consumer workloads → evaluate Nova with its own RPC endpoint.

Stylus: Rust contracts on Arbitrum

Stylus compiles Rust or C++ to WASM, coexists with Solidity in the same address space, and still uses eth_sendRawTransaction / eth_call from RPC clients.

cargo stylus check
cargo stylus deploy --private-key=$PK --endpoint=https://rpcfree.com/arbitrum-rpc

From viem or ethers, Stylus contracts look like ordinary ABI-bound contracts — same logs and calldata encoding.

Try it now

Copy and run in your terminal:

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

Or click to test live:

Method: Response time: CU cost:

Useful links

Arbitrum Documentation Explorer

Free vs Pro

Limit	Free (no signup)	Etox Pro
CU / month	10M	300M
CU / day	333,333	unlimited
Req / sec	10	100
Stylus contract calls	Yes	Yes
Arb-specific methods (arbtrace_*, nodeInterface)	Yes	Yes
Sequencer feed / streaming	—	On request
Archive data	Yes	Yes
API key	not required	included

Need more throughput? etox.io — Pro from $49/mo, 300M CU/month, 100 req/sec.

FAQ — Arbitrum

What is Arbitrum and how is it different from Ethereum?

Arbitrum is a Layer 2 scaling network built on top of Ethereum. Launched in 2021 by Offchain Labs, it’s one of the largest L2s by total value locked — billions across DeFi protocols like GMX, Camelot, and Aave.

Compared to Ethereum mainnet, Arbitrum offers ~250 millisecond confirmations instead of 12+ seconds, 10–100× cheaper transactions (often roughly $0.01–0.10), the same rollup security model posting data to Ethereum, and full EVM compatibility — any Ethereum dApp can deploy without code changes.

You use the same wallet (MetaMask, Coinbase Wallet, etc.) and ETH as the gas token — no separate currency needed for gas.

How fast are Arbitrum transactions, really?

Two answers depending on what fast means:

Soft confirmation: ~250ms. Your wallet shows the transaction as confirmed almost instantly, and most dApps treat this as final for UX purposes.
Hard finality on Ethereum: ~7 days. This is the dispute window for the optimistic rollup. For most activities (swaps, transfers, NFT mints) you don’t need to wait this out — the soft confirmation is enough.

The 7-day window mainly matters if you’re withdrawing back to Ethereum mainnet through the canonical bridge. For instant withdrawals, third-party bridges like Across, Hop, and Stargate handle it in minutes for a small fee.

How do I bridge funds from Ethereum to Arbitrum?

Three options:

Official Arbitrum Bridge at bridge.arbitrum.io — supports ETH and ERC-20s. Deposits take ~10 minutes, cost only the L1 gas fee.
Direct from exchanges — Coinbase, Binance, Kraken, and most major exchanges support direct withdrawals to Arbitrum. This skips the bridge and is often the cheapest option.
Third-party bridges (Across, Stargate, Hop, Synapse) — instant transfers from many chains, typically 0.05–0.3% fee.

For day-to-day use, withdrawing from your exchange straight to Arbitrum is simplest. For bridging within crypto (e.g. from Polygon to Arbitrum), use a third-party multi-chain bridge.

How do I add Arbitrum to MetaMask?

Visit chainlist.org/chain/42161 and click Add to MetaMask — one click adds it.

Manually:

Network name: Arbitrum One
RPC URL: https://rpcfree.com/arbitrum-rpc
Chain ID: 42161
Currency symbol: ETH
Block explorer URL: https://arbiscan.io

After adding, you’ll need some ETH on Arbitrum for gas. Bridge it from Ethereum or withdraw directly from an exchange that supports Arbitrum.

What is the difference between Arbitrum One and Arbitrum Nova?

They’re two separate chains by the same team, optimized for different use cases:

Arbitrum One (chain ID 42161) — the main network. Full security, posts data to Ethereum. Used by major DeFi (GMX, Camelot, Aave, Uniswap). This RPC endpoint serves Arbitrum One.
Arbitrum Nova (chain ID 42170) — uses a Data Availability Committee instead of full L1 data posting, making it cheaper. Slightly different security tradeoffs. Mostly used for gaming and social apps (e.g. Reddit Community Points on Nova).

If you’re doing DeFi or anything financial → use Arbitrum One. If you’re playing games or doing high-volume social activity where lower cost matters → consider Nova (separate RPC needed).

Does Arbitrum have its own token? What is ARB?

Yes — ARB is Arbitrum’s governance token, launched in March 2023 via airdrop to early users. Unlike ETH, ARB is not used for gas — it’s for voting on protocol decisions through the Arbitrum DAO.

You still pay all gas fees in ETH on Arbitrum, just like on Ethereum mainnet. You don’t need ARB to use the network. ARB is only relevant if you want to participate in governance (upgrades, treasury allocation, etc.). ARB is traded on most major exchanges and can be moved between Arbitrum One and Ethereum.