Approve EVM token

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

const options = {
  method: 'POST',
  headers: {Authorization: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    assetId: '0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29',
    blockchain: 'base',
    wallet: '0xf82567432381D1326484E5A9140ABCa4294f82D0'
  })
};

fetch('https://api.sand.etherfuse.com/ramp/evm/approve', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.sand.etherfuse.com/ramp/evm/approve"

payload = {
    "assetId": "0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29",
    "blockchain": "base",
    "wallet": "0xf82567432381D1326484E5A9140ABCa4294f82D0"
}
headers = {
    "Authorization": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "currentAllowance": "115792089237316195423570985008687907853269984665640564039457584007913129639935",
  "message": "Already approved — no transaction needed",
  "transaction": null
}

Approve EVM token

Generates an unsigned ERC20 approve() transaction that enables gasless offramps on EVM chains. When enabled for your organization, EVM offramp transactions no longer require the user to hold native gas tokens (e.g. ETH on Base) — 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; otherwise the offramp transaction fails on-chain.

Prerequisites:

The feature must be enabled for your organization (contact Etherfuse).
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 it in their wallet.
Once confirmed, create the offramp order via POST /ramp/order.

Approval amount: omit amount (recommended) to approve an unlimited amount once per token per chain; or pass amount in base units to approve a specific amount (consumed after each offramp). If a sufficient allowance already exists, the response has "transaction": null.

POST

ramp

evm

approve

Approve EVM token

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

const options = {
  method: 'POST',
  headers: {Authorization: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    assetId: '0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29',
    blockchain: 'base',
    wallet: '0xf82567432381D1326484E5A9140ABCa4294f82D0'
  })
};

fetch('https://api.sand.etherfuse.com/ramp/evm/approve', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.sand.etherfuse.com/ramp/evm/approve"

payload = {
    "assetId": "0xcC77c598d42f2f78Beb42C91d12B9d4041a5cE29",
    "blockchain": "base",
    "wallet": "0xf82567432381D1326484E5A9140ABCa4294f82D0"
}
headers = {
    "Authorization": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "currentAllowance": "115792089237316195423570985008687907853269984665640564039457584007913129639935",
  "message": "Already approved — no transaction needed",
  "transaction": null
}

Authorizations

Authorization

string

header

required

API key sent in the Authorization header.

Body

application/json

Request body for generating an EVM token-approval transaction.

Documentation schema for [evm_approve_proxy]. The handler forwards the body to the bridge service verbatim; this type only describes the expected shape.

assetId

string

required

The token contract address to approve (0x-prefixed, 40 hex chars).

blockchain

string

required

The EVM chain to approve on (currently base).

wallet

string

required

The user's EVM wallet address (0x-prefixed, 40 hex chars).

amount

string | null

Amount to approve in base units (token's smallest denomination). For a 6-decimal token, 10000000 = 10 tokens. Omit to approve the maximum (recommended — a one-time approval covers all future offramps).

Response

Approval transaction, or transaction: null if already approved

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User Authentication

Ramp API

Lookup API

Approve EVM token

Authorizations

Body

Response