curl --request POST \
  --url https://api.etherfuse.com/ramp/evm/approve \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "blockchain": "base",
  "wallet": "0xf82567432381D1326484E5A9140ABCa4294f82D0",
  "assetId": "0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29"
}
'

{
  "transaction": "{\"to\":\"0xcC77c598...\",\"data\":\"0x095ea7b3...\",\"value\":\"0\",\"gasLimit\":\"51861\",\"nonce\":39,\"gasPrice\":\"6000000\",\"chainId\":84532}",
  "message": "Approve transaction for gasless offramps on base"
}

Orders

Generate EVM token approval transaction

Generates an unsigned ERC20 approve() transaction that enables gasless offramps on EVM chains. When this feature is enabled for your organization, EVM offramp transactions no longer require the user to hold native gas tokens (e.g., ETH on Base) for the cross-chain bridging fee — Etherfuse covers the bridging cost and bundles it into the offramp fee.

This approval must be completed before creating an offramp order via POST /ramp/order for EVM wallets with this feature enabled. If the user has not approved, the offramp transaction will fail on-chain.

Prerequisites:

This feature must be enabled for your organization. Contact Etherfuse to enable sponsored EVM offramps for your org and sub-orgs.
The user must have a registered EVM wallet on a supported chain.

Flow:

Call this endpoint to get the approval transaction
Have the user sign and submit the transaction in their wallet
Once confirmed, create the offramp order via POST /ramp/order

Approval amount options:

Omit amount (recommended): Approves for an unlimited amount. The user only needs to do this once per token per chain, and all future offramps will work without needing another approval.
Pass amount: Approves for a specific amount in base units. The amount should match what you plan to offramp. After the offramp, the approval is consumed and you will need to call this endpoint again before the next offramp.

If the user has already approved a sufficient amount, the endpoint returns "transaction": null with a message indicating no approval is needed.

The amount field is in base units (e.g., for a token with 6 decimals, pass 10000000 for 10 tokens).

POST

/

ramp

/

evm

/

approve

curl --request POST \
  --url https://api.etherfuse.com/ramp/evm/approve \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "blockchain": "base",
  "wallet": "0xf82567432381D1326484E5A9140ABCa4294f82D0",
  "assetId": "0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29"
}
'

{
  "transaction": "{\"to\":\"0xcC77c598...\",\"data\":\"0x095ea7b3...\",\"value\":\"0\",\"gasLimit\":\"51861\",\"nonce\":39,\"gasPrice\":\"6000000\",\"chainId\":84532}",
  "message": "Approve transaction for gasless offramps on base"
}

Authorizations

Authorization

string

header

required

API key for authentication. Pass the key directly (e.g., Authorization: your-api-key). Do not use a Bearer prefix.

Body

application/json

blockchain

enum<string>

required

The EVM chain to approve on

Available options:

base

Example:

"base"

wallet

string

required

The user's EVM wallet address

Pattern: ^0x[a-fA-F0-9]{40}$

Example:

"0xf82567432381D1326484E5A9140ABCa4294f82D0"

assetId

string

required

The token contract address to approve

Pattern: ^0x[a-fA-F0-9]{40}$

Example:

"0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29"

amount

string

Amount to approve in base units (token smallest denomination). For a token with 6 decimals, 10000000 = 10 tokens. If omitted, approves for the maximum amount (recommended for one-time approval).

Example:

"10000000"

Response

Approve transaction generated (or already approved)

transaction

string | null

JSON-serialized unsigned transaction for the user to sign. Null if the user has already approved a sufficient amount.

message

string

Human-readable status message

currentAllowance

string

Current token allowance (only present when already approved)

List orders (with pagination)Swap assets

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