Arc for token teams

Arc is Circle's chain, id 5042. Most of it behaves like any other EVM chain, but a few differences matter enough to catch people out, and one of them will break your maths.

USDC is the gas token

There is no separate coin to buy before you can transact. Fees are paid in USDC, which means your costs are denominated in dollars and do not move with anything. For a team budgeting a launch, that is a genuine simplification.

It also means everyone who can transact at all already holds the asset any contract would want to charge in. Lockbox charges its fees in it for exactly that reason.

The decimals trap

This is the one that costs people a day. The same USDC balance reports two different denominations depending on how you ask.

• As the native balance, it behaves like ether and carries 18 decimals. A balance of 24.72 USDC reads as 24717056000000000000.
• Through the ERC-20 interface, it reports USDC's usual 6 decimals. The same balance reads as 24717056.

Both describe the same money. If you hardcode either, you will be wrong half the time. Read decimals from the token contract for anything going through the ERC-20 interface, and treat the native balance as 18 decimals.

No ETH, and no wrapped ETH

Arc has no native ether and no canonical WETH. If your contracts or tooling assume a wrapped native token exists, that assumption does not hold here. Stablecoins are the pairing assets, USDC and EURC rather than ETH.

Less tooling, and fewer people watching

Arc is newer and quieter. There are fewer explorers, fewer indexers, fewer bots and fewer people who have already hit the problem you are about to hit. Some infrastructure you would take for granted elsewhere is simply not there yet.

Two practical consequences. Verify your contracts on the Arc explorer, because with less tooling around, readable source is doing more of the work of establishing what your contract does. And expect to check things yourself rather than assuming someone else already has.

One more, worth knowing if you are writing scripts: the public RPC caps event log queries at 100,000 blocks per request, so anything scanning history has to page through in chunks.

What Lockbox runs on Arc

Everything that runs on Robinhood Chain, with fees priced in USDC: locks and vesting with cliffs, batch vesting from a CSV, transferable vaults at 50 USDC, Multisend for paying many wallets at once, and burning, which is free. Every contract has its source verified on the Arc explorer, and the addresses are listed here.

As far as we can tell there is no other token locker on Arc. That is why we are there, and it is also a reason to check our contracts rather than assume a crowd has already done it. What they can and cannot do.

More detail on the mechanics of locking there: locking tokens on Arc.