Accept USDC and USDT on Optimism with Paymos

Why Optimism for crypto payments

Optimism is the original OP Stack rollup — the framework that now underpins Base, Worldcoin, Mode, Zora, and a growing list of Superchain L2s. Its user base is DeFi-native and OP-aligned: Velodrome, Synthetix, Aave's OP deployment, and a long list of protocols that chose Optimism early. For a merchant, it's the right rail when your audience leans into the OP brand or uses Optimism-native DeFi. That audience overlaps heavily with Arbitrum's, but each L2 has its loyalists — accepting both costs nothing extra and captures customers from either side without forcing a bridge.

Supported stablecoins on Optimism

The panel above shows the live set: USDC and USDT, both native ERC-20. Circulation here is thinner than on Ethereum L1 or Arbitrum, but both tokens settle the same way.

How confirmations work on Optimism

Optimism settles a block every 2 seconds. The confirmation count Paymos waits for tracks the invoice amount, not a flat number: a sub-$100 ticket clears almost at once, while a five-figure B2B transfer waits for a deeper count — still inside a minute on a 2-second chain — to guard against a sequencer hiccup or a rollup-state reorg. The threshold is tuned operationally; live values surface in your dashboard.

Fees and gas

The customer pays the network fee in ETH on Optimism — typically a few cents per ERC-20 transfer, occasionally more when L1 data costs spike. A wallet with zero ETH on Optimism cannot broadcast even if it holds USDC.

Paymos pricing on Optimism: 1.0% Standard, 0.3% Enterprise on request. Acceptance and the gas to sweep each payment both sit inside that 1.0% — no separate line for either. Withdrawals carry no Paymos commission: you pay a network fee set below Optimism's own cost, and we absorb the difference . Cash out in USDC or USDT to any whitelisted wallet.

Compared to a typical crypto gateway

Most gateways bolt a single confirmation count onto an L2 and charge it against a $30 order and a $30,000 invoice alike. Paymos tiers that depth, so a small ticket isn't stuck behind the margin a treasury transfer needs. The integration contract is the same on Optimism as on every Paymos chain: each state change posts an HMAC-SHA256-signed webhook, a dead endpoint is retried 11 times across roughly 32 hours, and your own external_order_id keys the invoice — a retried call returns the original rather than a duplicate, with no separate idempotency header.

What we don't do on Optimism

We credit native USDC and native USDT only — not bridged USDC.e from before Circle issued directly on Optimism, and not any wrapped DAI, since Sky never made Optimism a canonical DAI chain. No swap and no fiat off-ramp sit in the path either: the balance stays in whichever of the two coins the buyer sent. We don't fund the customer's ETH for gas. And the optimistic-rollup 7-day exit to Ethereum L1 never lands on a merchant — payments confirm and balances withdraw on Optimism itself, and consolidating up to L1 later is your treasury's decision, not ours.

Frequently asked questions

What's the difference between Optimism and Base?

Architecturally they are close cousins — Base runs on the same OP Stack Optimism authored, so the rollup internals barely differ. The split is in who runs them and who uses them. Base is operated by Coinbase and its traffic skews US retail flowing out of Coinbase accounts; Optimism is operated by OP Labs and its base is more globally spread and DeFi-native. For a merchant the call is audience, not architecture: enable the chain your buyers already hold balance on, or enable both and let them self-select.

Should I accept Optimism if I already accept Arbitrum?

If any slice of your buyers lives in the OP ecosystem, yes. Turning on a second L2 costs you nothing — it appears as one more option at checkout, and the buyer chooses. The two audiences overlap but aren't identical: an Optimism-loyal buyer won't always carry a balance on Arbitrum. If your analytics already show Optimism wallets paying you, the case is made; if every buyer is strictly Arbitrum-DeFi, the upside is thinner.

What is OP Stack?

It is the open-source codebase Optimism built to spin up a rollup, and the reason Base, Zora, Mode, and the rest of the Superchain feel mechanically alike. Each chain ships from that shared code yet keeps its own state, its own sequencer, and its own economy. For acceptance the practical upshot is simple: a Superchain L2 confirms the way you'd expect an OP Stack chain to, but its balances and traffic are entirely its own — Optimism's USDC is not Base's USDC.

Can a customer pay me from Coinbase to Optimism?

Yes. Coinbase supports USDC withdrawals to Optimism. The customer picks Optimism on withdrawal; the USDC arrives at your Paymos deposit address. Note that Coinbase also has its own L2 (Base) — make sure the customer picks the right network if you only have one enabled.

What gas token does Optimism use?

ETH, same as Arbitrum and Base. A customer paying USDC on Optimism needs a small ETH balance on Optimism — a few cents covers the transaction.

Are fault proofs important for Optimism's security?

Yes, structurally. Permissionless fault proofs — the Cannon prover — went live on OP Mainnet in June 2024, letting anyone challenge an invalid state transition rather than relying on a whitelisted challenger set as the interim model did. For a merchant the takeaway is narrower: the chain reaches and holds finality, which is all an accepted payment needs. The proof system is what keeps that finality honest.