Measured, not quoted

Arc mainnet: what actually works

Claim USDC and APEX on Arc, three times a day

Real dollars from an on-chain pot, plus APEX from the drip vault. The contracts fix the amounts, the 8-hour cooldown and the daily totals, and have no withdraw function: money leaves only as claims. Everyone gets the same claim.

Reading the pot from the chain…
Agents: GET /api/arc/faucet/challenge/{address}, sign it, POST /api/arc/claim {address, signature}. No captcha, no gas needed. Contract source: ApexFaucetArc.sol. Status: /api/arc/faucet.

Circle's Arc L1 went public on 16 September 2026. Everything below was measured against the live chain that day, because several of these differ from the documentation.

Checked 2026-09-16 from apexfaucet.xyz. Where a fact contradicts the docs, that is noted.

APEX is on Arc: the same token, moved by burning

No new token. APEX only exists on Arc after the same amount was burned on X1: the Arc contract can never mint more than X1 had, and every mint names the X1 burn it came from. Ten million APEX crossed first, into a drip vault that releases 1% a week to the faucet, forever. No owner, no withdraw.

Reading APEX on Arc from the chain…

How it grows: every USDC paid to us on Arc (a house, a paid API call) lands in a split contract that can only do two things: half to the USDC claim pot, half swapped for APEX on this pool and sent to the vault. Nobody can withdraw it. So revenue raises both the dollar claim and the APEX price, and nothing else does. Contract 0x160168706aab75f6d6b951329706c90f32b25c56, source ApexRevenueSplit.sol.

Move your own APEX: on X1, burn APEX in a transaction that also carries the memo APEX|ARC|0xYourArcAddress, then POST /api/arc/migrate {"x1Signature": "…"}. The same amount is minted to your Arc address; each X1 signature mints once.

Pool: Uniswap v4 on Arc, APEX/USDC, 0.3% fee, pool id 0xcdf5b513… · Token 0x59933f316417c89d9dc5107b30f08c99b774ea9d · Migrator 0x966644f5558e42b31846f4b7e103a40ecad3874b · Vault 0x2d644a0aa8e821b31707228f23c387c84134049a · Source ApexArc.sol · Status /api/arc/apex

The one that breaks integrations

USDC is the native gas token, and it moves as value — not as ERC-20 transfers

Paying someone USDC on Arc is a plain value transfer: the amount is in tx.value at 18 decimals. It does not emit an ERC-20 Transfer log.

In a 12-block sample, 171 of 661 transactions carried native value and the token contract at 0x3600000000000000000000000000000000000000 emitted zero Transfer logs. That contract is a view of the same balance at 6 decimals.

Consequence: a payment verifier written from the documentation — watching for ERC-20 Transfer events — reads every incoming payment as zero. Watch tx.value instead, and remember the 18-vs-6 decimal difference between the native amount and the ERC-20 view.

Connection facts

ItemValue
Mainnet chain ID5042 (0x13b2)
Mainnet RPChttps://rpc.mainnet.arc.ioopen, no key
Testnet chain ID5042002
Testnet RPChttps://rpc.testnet.arc.ioopen
USDC (ERC-20 view)0x36000000000000000000000000000000000000006 dp
USDC as gas / valuenative18 dp
Block timeabout 0.5 s, deterministic finality on inclusion

The docs state that mainnet endpoints are permissioned and require credentials during the private phase. As of launch day that is stale: rpc.mainnet.arc.io answers eth_chainId and eth_getLogs without any key or allowlist.

Limits that bite

LimitObserved
eth_getLogs rangeCapped by results, not blocks: a wide query returns query exceeds max results 2000, retry with the range … and suggests a window of a few blocks. Plan for cursor-style scanning, not fixed block windows.
Minimum base fee20 Gwei floor, enforced at the mempool.
PREVRANDAOAlways returns 0 — there is no on-chain randomness. Anything needing a random draw needs an external oracle.
BurningForbidden. Transfers to the zero address revert.
BlocklistEnforced at protocol level. Because gas is USDC, a blocklisted address cannot pay gas at all — it is not merely a frozen asset.

Agent payments, on launch day

Arc is positioned around machine-to-machine payments. What is actually live on mainnet, as opposed to testnet, is narrower than the marketing suggests.

ThingStatus on Arc mainnet
ERC-8004 IdentityRegistrybytecode present at 0x8004A169FB4a3325136EB29fA0ceB6D2e539a432, though the docs list testnet addresses only
ERC-8004 ReputationRegistrybytecode present at 0x8004BAa17C55a88189AE136b182e5fdA19dE9b63
Circle x402 service directoryemptyapi.circle.com/v2/x402/discovery/resources?network=eip155:5042 returns total: 0, against 990 on Base
Coinbase CDP x402 facilitatorArc not supported

Consequence worth knowing: listings in Circle's directory are created as a side effect of a facilitator settling a payment — there is no submission form, and POST to the discovery endpoint returns 404. With no facilitator settling on Arc yet, nobody can be listed on Arc, however much they have built. That is a door that is closed for everyone, not a gap to fill.

Getting USDC onto Arc

Circle's CCTP moves USDC only — no other asset bridges. Arc is CCTP domain 26; Solana is domain 5, and a Solana → Arc transfer takes roughly 25 seconds at standard speed. There is a free testnet faucet at faucet.circle.com giving 20 USDC every 2 hours with no account, though it is reCAPTCHA-protected, so a person has to click it.

Agents registered on Arc

ERC-8004 is the on-chain agent registry. This is every agent registered on Arc mainnet, read from the registry contract, with the name each one publishes about itself. APEX Faucet is number 1.

#NameSays it doesServicesOwner

What we run here

Get here from any chain: live quotes for moving 2 USDC into Arc from fourteen chains, with the real cost and time, refreshed every ten minutes.

Touchstone: an assay is a real buy and sell of a token in one transaction, reverted, with only the mark kept on chain: verdict, cost, streak. Anyone can pay for one; the fee feeds the faucet pot and the APEX vault.

Grow on Arc: put USDC to work in the APEX/USDC pool from your own wallet in one click. The position is yours alone, earns the pool's fees, and comes out in one click. A read-only link shows deposit and value from the chain to anyone you choose.

Arc Exit Check: paste a token, we buy it and sell it straight back inside one eth_call, through its hook, spending nothing, and tell you whether you can get out and what it costs. Free one at a time; bulk is paid in USDC on Arc and feeds the pot.

Arc Sniper Watch: every new pool on Arc, who bought it first and how fast, read from the chain every five minutes. Born the afternoon a bot sniped our own pool in 33 seconds.

Arc Embassy: a cobalt cabin at plot (-6, 6) in APEX City, built on X1 with 1,000 APEX burned, so the two chains have a porch in common.

A USDC faucet, live on Arc mainnet (above): contract 0x53fb2e89834050afaa9b3090a1fc9d1064615805, deployed 2026-09-16, source published at /arc/ApexFaucetArc.sol.

apexfaucet.xyz accepts USDC on Arc as a payment rail beside card and XNT: a $5 house in a 3D city, and paid API endpoints priced per call. Payment is verified by reading tx.value on chain — the payer sends the transfer themselves and nothing is custodial.

Buy a house for $5 · Hire us to build on-chain modules · llms.txt

Written by the team at apexfaucet.xyz. Every figure here was read from the live chain or a live API on 2026-09-16, not copied from documentation. Where we could not verify something we left it out rather than guessing.