API Overview

Uapi provides a high-performance, non-custodial crypto payment infrastructure for global merchants. Our API makes complex blockchain interactions as simple as traditional payments.

Base URL

https://uapi.io/api/v1

1 Authentication

All requests must include your API Key in HTTP headers. Keys are split into Test Key (sandbox) and Live Key (production).

HTTP Header
X-API-KEY: sk_live_xxxxxxxxxxxxxxxxxxxxxxxx

Domain Security Validation

To prevent API abuse, your request domain must be bound in Merchant Console > Website Management. For direct backend requests (without Origin header), explicitly include the domain parameter in the payload. Unbound domains will be rejected.

Integration Flow

1

Create Order

Merchant calls the API with amount and network, then receives a payment link (payment_url).

2

User Pays

Redirect users to checkout, where they complete payment via QR scan or transfer.

3

Confirm & Callback

After on-chain confirmation, the system sends a webhook and updates order status automatically.

No-Code Integration

If you do not want to write code, you can use our Payment Link feature:

  • Generate a dedicated payment page in one click from the merchant console.
  • Set fixed amounts or allow customers to enter custom amounts.
  • Share the link directly through social media, Telegram, or WhatsApp.
  • After successful payment, settlement details remain available in your dashboard.

Create Order

POST

Create a brand-new payment order and receive a checkout link.

Endpoint

/order/create.php
Parameter Type Required Description
amount Float YES Order amount (USDT)
chain String YES Network: trc20, erc20, bsc, solana, polygon, etc.
merchant_order_id String YES Your merchant order number (unique)
notify_url String NO Webhook URL. A POST callback will be sent after successful payment.
domain String YES* Required for server-to-server requests (e.g., curl/backend SDK). Use your bound website domain, e.g. yoursite.com. It can be omitted if Origin/Referer is present. 
{
  "status": "success",
  "data": {
    "order_no": "PAY2024...",      // System-generated payment order number    "amount": "100.001234",        // Payable amount with anti-collision random decimal    "payment_url": "https://...",  // Checkout URL    "expire_in": 600               // Order validity period (seconds)  }
}

Check Status

GET

Poll or query the latest order payment status on demand.

Endpoint

/order/status.php?order_no=PAY... 
// Paid response{
  "status": "paid",
  "tx_hash": "0x123abc...",  // On-chain transaction hash  "amount_paid": "100.001234"
}

Webhook Callback

Once the on-chain transaction is confirmed, the system immediately sends a POST callback to your notify_url.

If notify_url is omitted when creating an order, the system will automatically use the default webhook URL in Merchant Console > API Settings.

Signature Verification

// Recommended: HMAC-SHA256
X-UAPI-Signature: hmac_sha256(order_no + amount + merchant_order_id + timestamp, api_key)
// Legacy: MD5 (for backward compatibility)
sign: md5(order_no + amount + merchant_order_id + api_key)

Response requirement: your receiver must return HTTP 200, or include success in response body. Otherwise the system retries up to 3 times (about 1s and 2s backoff).

Order State Machine

Status Description
pending Created and waiting for user payment with the exact amount.
paid On-chain amount and address matched; tx hash recorded and callback sent.
expired Not paid within validity period (usually 10-20 minutes); automatically marked as expired.

Rate Limits & Idempotency

  • API Rate Limit: The free plan is limited to 100 calls per day. Pro and Enterprise provide higher concurrency quotas.
  • Idempotency: Ensure merchant_order_id is unique in your system. Re-submitting the same order ID returns existing order data instead of creating a new order.
  • Concurrency Handling: Use distributed locks when consuming webhooks to prevent duplicate processing caused by concurrent callbacks.

Supported Networks & Precision

Network (Slug) Precision Token Notes
trc20 6 USDT Tron network with fast confirmation and very low fees.
bsc 18 USDT/BNB Binance Smart Chain.
erc20 18 USDT/ETH Ethereum mainnet (higher gas fees).
polygon 6/18 USDT/MATIC Layer 2 scaling network.
solana 6/9 USDT/USDC High-performance non-EVM chain.
arbitrum 18 USDT Ethereum L2 rollup network.

Tools & Versions

TLS Requirement

For security, our API requires TLS 1.2 or higher. Older SSL/TLS versions cannot establish a connection.

Data Encoding

All request and response bodies must use UTF-8. Ensure your Content-Type is set to application/json.

Developer FAQ

Can order expiration be customized?

Default validity is 10-20 minutes. For longer expiration, contact support or configure it in Merchant Console > API Settings. Longer windows may increase amount-collision probability.

Why does the actual payable amount include random decimals?

This enables precise order matching in non-custodial wallets. Since multiple transfers may share the same integer amount on-chain, adding a tiny random decimal (e.g., 100.001234) keeps each order unique under your wallet address.

Multi-language Integration Examples

PHP 
$apiKey = 'sk_live_xxx';
$data = [
    'amount' => 100.0,
    'chain' => 'trc20',
    'merchant_order_id' => 'MY_ORDER_001',
    'notify_url' => 'https://yoursite.com/callback',
    'domain' => 'yoursite.com'
];

$ch = curl_init('https://www.uapi.io/api/v1/order/create.php');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'X-API-KEY: ' . $apiKey,
    'Content-Type: application/json'
]);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
$result = json_decode($response, true);
echo $result['data']['payment_url'] ?? 'Create order failed';
Node.js (Axios) 
const axios = require('axios');

const createOrder = async () => {
  const { data } = await axios.post('https://www.uapi.io/api/v1/order/create.php', {
    amount: 100.0,
    chain: 'trc20',
    merchant_order_id: 'MY_ORDER_001',
    notify_url: 'https://yoursite.com/callback',
    domain: 'yoursite.com'
  }, {
    headers: {
      'X-API-KEY': 'sk_live_xxx',
      'Content-Type': 'application/json'
    }
  });
  console.log(data.data.payment_url);
};