Kast Optimism Card, explained: USDC on OP Mainnet, costs and getting money out

The Kast Optimism Card is the KAST Visa card funded with USDC sent over Optimism. KAST takes USDC there with no KAST fee and credits it 1:1 as dollars. Optimism is deposit-only, so withdrawals leave on Arbitrum, Solana or Ethereum.

What is the Kast Optimism Card?

The Kast Optimism Card is the regular KAST Visa card, topped up with USDC sent over Optimism, the Ethereum layer 2 that wallets also list as OP Mainnet. There is no special card: Optimism is one of the 13 networks you can pick when you deposit.

It makes sense if your USDC already sits on Optimism, for example after using a DeFi app there. You send it straight to KAST instead of bridging back to Ethereum and paying mainnet gas.

KAST Receive stablecoin screen with coin, network, QR code and address
Kast Optimism Card: pick USDC, then the network

How to deposit USDC on Optimism to KAST

USDC is the only coin KAST accepts on Optimism:

  1. In the KAST app, tap Receive and choose Stablecoin.
  2. Pick USDC, then Optimism from the network list.
  3. Copy the address with the copy button.
  4. Send USDC on Optimism from your wallet or exchange to that address.

KAST charges nothing and credits it 1:1 in dollars. At least $1 has to arrive after network fees. If you're new, our Kast Card sign up page covers opening the account.

KAST app USDC balance with Deposit and Withdraw buttons
Kast Optimism Card: USDC balance after a deposit

What Optimism costs with KAST

Optimism sits with Arbitrum, Base and Avalanche in KAST's moderate-fee group: transfers usually settle in under a minute and gas runs from a few cents to under a dollar. Deposits carry no KAST fee.

Card payments in US dollars are free, other currencies carry a 0.5% to 1.75% FX fee, and the full list is on our Kast Card fees page.

Phone payment approved at a card terminal on a restaurant table
Kast Optimism Card payment approved at a terminal

Getting money out when Optimism is deposit-only

KAST doesn't send out on Optimism. USDC can leave on Arbitrum ($0.20 + 0.1%), Solana ($1 + 0.1%) or Ethereum ($6 + 0.1%), with a $5 minimum.

Arbitrum is the natural pick for Optimism users: another Ethereum layer 2, the same 0x wallets, and the cheapest withdrawal KAST offers. Our Kast Arbitrum Card page has the details, and the Kast Base Card page covers the other USDC-only layer 2.

Spending Optimism USDC with the Kast Card

Once the USDC lands it is a dollar balance you can spend anywhere Visa works. Cashback is paid in US dollars: up to 8%, with 1.5% on the free Standard tier and more on the paid tiers.

KAST: send in crypto, spend in stables
Kast Optimism Card: send crypto, spend stablecoins
Black KAST Visa card tapped on a card reader
Kast Optimism Card at a card reader
KAST USD cashback by tier: 1.5%, 2% and 3%
Kast Optimism Card cashback by tier

Optimism, Base or Ethereum? Getting the network right

Optimism addresses look the same as Ethereum, Base and Arbitrum ones, so a wallet won't warn you about a mix-up. Pick USDC and Optimism in KAST first, then copy the address, and choose Optimism (or OP Mainnet) on the sending side.

Don't send USDT, ETH or OP on Optimism: KAST doesn't support them there. If funds go out on the wrong network or coin, recovery isn't guaranteed; when it works it takes 1 to 2 weeks, costs a fee and returns the money to the sending wallet.

Kast Optimism Card referral code: 6MHGEMGE

The referral code for the Kast Optimism Card is 6MHGEMGE. It works whatever network you fund with: $20 after your first $100 of card spend and 10% off a paid membership. Sign up through app.kast.xyz/referral/6MHGEMGE and it is added for you.

6MHGEMGE Sign up with the code →

The requirements for each reward are listed on our KAST referral code page.

Information only, not financial advice. This site is independent and not operated by KAST. Network facts from KAST Concierge (supported stablecoins, tokens and blockchains, fees) and KAST's posts on X, checked Oct 2026. Images: KAST on X.