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Base Base is supported for onramps and offramps. As an EVM chain, assets are plain ERC-20 contracts and offramps need a one-time token approval before the customer can sell — with gasless offramps, the user doesn’t even need ETH. The end-to-end flows live in the Onramps and Offramps guides.

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Supported operations

OperationSupported
Onramp (fiat → token)✓
Offramp (token → fiat)✓
Swap (token → token)✗ — not yet on Base (Stellar / Solana / Monad only)

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Asset identifiers

Base assets are identified by the raw token contract address only — e.g. 0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29.
Do not prefix with a symbol. Using SYMBOL:0x... (the Stellar-style format) on an EVM chain returns UnsupportedBlockchain. Pass just the 0x… address from GET /ramp/assets?blockchain=base.

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Stablebond addresses

Live token-contract addresses for every stablebond on Base, each linked to Basescan:

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Offramps: approve the token first

Selling an ERC-20 requires a standard approve() so Etherfuse’s contracts can move the token. Generate that approval with POST /ramp/evm/approve before creating the offramp order — otherwise the offramp transaction fails on-chain. 
curl -X POST https://api.sand.etherfuse.com/ramp/evm/approve \
  -H "Authorization: <api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "blockchain": "base",
    "wallet": "0xf82567432381D1326484E5A9140ABCa4294f82D0",
    "assetId": "0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29"
  }'
  • Omit amount (recommended) to approve the maximum — a one-time approval per token per chain covers all future offramps. Or pass amount in base units to approve a specific amount.
  • If a sufficient allowance already exists, the response is {"transaction": null} — nothing to sign, go straight to the order.
  • Otherwise, have the user sign and submit the returned transaction, then create the offramp via POST /ramp/order.

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Gasless offramps

When gasless offramps are enabled for your organization, Etherfuse covers the native gas (ETH on Base) for the offramp and bundles that cost into the offramp fee — so your users don’t need to hold ETH.
Minimum offramp size. Because the combined fee can never exceed 50% of the order, very small offramps are rejected with OrderTooSmall (“Combined fee … exceeds maximum (5000 bps / 50%)”). The bundled gas cost is roughly $0.50, so offramp at least ~50 CETES (or equivalent) at a time. See Errors.
Gasless offramps and the POST /ramp/evm/approve flow are feature-gated per organization — contact Etherfuse to enable them.

Onramps

Offramps