arb.eth: ENS usernames for Arbitrum One

Live activity

Watch the namespace come alive.

Every claim, primary-name switch, and record update is a resolvable ENS event. This is what Arbitrum's feed looks like on day one.

Live

1,203 names claimed Ξ12.03 revenue ~2s to issue

issuance.log — ccip-read gateway

Simulated preview. In production this feed reads directly from the offchain resolver's issuance log.

How it works

Two steps. No new protocol, no migration, no lock-in.

arb.eth is already an ENS name, so it can be the root of a username system Arbitrum controls end to end, no import required.

01

Choose how arb.eth names resolve

Because arb.eth is already a native ENS name, there is nothing to import. Arbitrum can choose the infrastructure that best fits its needs:

Offchain: use a CCIP-Read resolver for instant, gasless issuance at unlimited scale.
Ethereum mainnet: store names and records directly on ENS for maximum onchain permanence.
Arbitrum L2: issue and manage names on Arbitrum, with lower costs and native integration into the Arbitrum ecosystem.

The resolution model can also evolve over time without requiring users to migrate to a new namespace.

02

Users claim and use their arb.eth name

Users claim a name such as alice.arb.eth directly through the Arbitrum app. The name maps to their Arbitrum address and can be used anywhere ENS is supported.

Instead of sending to 0x4f3a…9c21, wallets and apps can send to alice.arb.eth. Reverse resolution can also display the name across compatible wallets, explorers, and dapps.

Precedent

The pattern is proven at exchange scale.

This exact architecture, a company domain imported into ENS with gasless offchain subnames, is already running in production:

world.id

World

Usernames for World App's millions of verified users: a DNS name imported into ENS, the same architecture as arb.eth.

uni.eth

Uniswap

Free wallet usernames in the Uniswap mobile app, issued gaslessly with CCIP-Read.

base.eth

Coinbase / Base

Basenames, the identity layer for an entire L2, built on ENS infrastructure.

AI agents

First-class for AI agents, out of the box.

The same gateway that answers wallets can answer agents. Names become machine-readable identity: Claude, Cursor, and any MCP client can resolve, verify, and claim arb.eth names with no keys and no scraping.

MCP server

One URL turns every MCP client into a arb.eth resolver: read-only tools, nothing to install.

{
  "mcpServers": {
    "arb-eth": {
      "url": "https://arb.eth/api/mcp"
    }
  }
}

resolve_name name → address
reverse_resolve address → primary name
check_availability name → free / taken
register_name claim a name for an agent

llms.txt

Machine-readable docs at the domain root, linked from robots.txt, so an LLM learns to resolve names without reading the site.

# https://arb.eth/llms.txt
arb.eth: ENS usernames on
Arbitrum One.

Resolve:  alice.arb.eth → 0x…
Reverse:  0x… → alice.arb.eth
Full spec: /llms-full.txt
  (contracts, gateway API, records)

/llms.txt concise overview (live)
/llms-full.txt full technical context (live)

Agents claim names too

An agent registers myagent.arb.eth over plain HTTP and holds it in its own wallet: instant, gasless, programmatic.

# quote
GET /quote?name=myagent

# claim (0.01 ETH via x402)
POST /register
{ "name": "myagent",
  "owner": "0xAgentWallet" }

x402 agent-native HTTP payments
0.01 ETH flat fee per name

Why ENS

Build on the namespace wallets already speak.

A proprietary naming system starts at zero integrations. ENS starts with all of them.

	Custom naming system	ENS via arb.eth
Works wherever ENS works	Requires each app to integrate	Day one, no integration asks
Cost per name	Depends on design	0.01 ETH flat (offchain issuance)
Who controls the namespace	Arbitrum	Arbitrum (via any DNS domain or ENS name like arb.eth)
Multi-chain addresses (BTC, SOL, L2s)	Build it yourself	Native ENS record types
Time to ship	Quarters	Instantly: import + gateway + claim UI

MetaMask Uniswap Blockscout Etherscan Coinbase Wallet Rainbow

The same infrastructure behind world.id, base.eth, uni.eth, and gemini.eth.