Convert currencies

Stablecoin Account API Publisher Disclaimer Conversions exchange one currency in your account for another — crypto to fiat, fiat to crypto, or crypto to crypto — at a rate you lock in advance. The flow is always two calls: create a quote, then create the conversion referencing it before the quote expires.

Prerequisites

An API token sent as the x-auth-token header
Sufficient available_balance in the selling currency

Step 1: Create a quote

Call Create Quote with the currency pair, the amount, and which side the amount fixes:

curl -X POST https://api-sandbox.uqpaytech.com/api/v1/ramp/conversion/quote \
  -H "x-auth-token: YOUR_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "sell_currency": "USDT",
    "buy_currency": "SGD",
    "amount": "100",
    "fixed_currency": "USDT"
  }'

fixed_currency names the side amount applies to — fix the sell side to spend an exact amount, or the buy side to receive an exact amount.

Pair restrictions: for crypto-to-crypto, only USDT paired with one other supported coin is allowed. If either side is a volatile asset (for example BTC or ETH), only USDT can be the fixed currency.

Response:

{
  "code": 200,
  "message": "Success",
  "data": {
    "quote_id": "958813b7-8523-4b93-862e-46eddb87b56d",
    "sell_currency": "USDT",
    "sell_amount": "100",
    "buy_currency": "SGD",
    "buy_amount": "133.84",
    "currency_pair": "USDTSGD",
    "direct_rate": "1.3384723",
    "inverse_rate": "0.74712043",
    "processing_fee": "0",
    "network_fee": "0",
    "valid_from": "2026-04-27T10:47:26+08:00",
    "valid_to": "2026-04-27T10:50:26+08:00"
  }
}

The quoted rate holds between valid_from and valid_to. If the window passes before you execute, request a new quote — an expired quote_id is rejected.

Step 2: Execute the conversion

Call Create Conversion with the quote_id and the amounts exactly as quoted, plus an idempotency key:

curl -X POST https://api-sandbox.uqpaytech.com/api/v1/ramp/conversion \
  -H "x-auth-token: YOUR_API_TOKEN" \
  -H "x-idempotency-key: $(uuidgen | tr '[:upper:]' '[:lower:]')" \
  -H "Content-Type: application/json" \
  -d '{
    "quote_id": "958813b7-8523-4b93-862e-46eddb87b56d",
    "sell_currency": "USDT",
    "sell_amount": "100",
    "buy_currency": "SGD",
    "buy_amount": "133.84",
    "reason": "treasury rebalance"
  }'

The response returns the conversion order — order_id, short_order_id, status, both currency sides, the quote_price used, and fees. order_type is Sell or Buy depending on direction.

Step 3: Track the conversion

Conversion status flows through Submitted / Pending to Success, Failed, or Submit Failed. Updates arrive on the Conversion webhook:

Event type	Meaning
`ramp.conversion.trade.pending`	Conversion in progress
`ramp.conversion.trade.completed`	Conversion completed
`ramp.conversion.trade.failed`	Conversion failed

Query on demand with Retrieve Conversion or reconcile with List Conversions (filter by order_status, order_id, or balance_currency). Completed conversions carry a settle_time.

Create Quote API
Create Conversion API
Conversion webhook
Manage asset balances — conversions appear as Sell / Buy / Swap in the ledger

Getting Started

Assets & Balances

Deposits

Withdrawals

Conversions & Transfers

Reference

Step 1: Create a quote

Step 2: Execute the conversion

Step 3: Track the conversion

​Step 1: Create a quote

​Step 2: Execute the conversion

​Step 3: Track the conversion

​Related

Step 1: Create a quote

Step 2: Execute the conversion

Step 3: Track the conversion

Related