What is OpPay?

OpPay is a Bitcoin-native payment SDK that lets any website accept BTC payments in minutes — with zero KYC, zero bank accounts, and a fee of just 0.01% per transaction.

Quick Start

Add a working Bitcoin payment button to any website in under 2 minutes. No backend required for the basic flow.

<!-- 1. Load the SDK -->
<script src="https://cdn.oppay.io/v1/pay.js"></script>

<!-- 2. Your pay button -->
<button onclick="openPayment()">₿ Pay with Bitcoin</button>

<!-- 3. The call -->
<script>
function openPayment() {
  OpPay.open({
    amount:      49.99,
    btc:         0.000495,
    currency:    'EUR',
    merchant:    'My Shop',
    description: 'Order #1234',
    api_key:     'op_live_xxxxxxxxxxxx',
    onSuccess: (d) => console.log('Paid!', d.txId),
    onFailure: (d) => console.log('Failed:', d.reason),
    onCancel:  () => console.log('Cancelled'),
  });
}
</script>

Integration Guide

OpPay works on any stack. Choose your platform below.

Shopify

In your Shopify theme editor, go to Online Store → Themes → Edit code. Open theme.liquid and paste the SDK script before </head>. Then add an OpPay button in your product template using a Liquid snippet.

WooCommerce

Install the OpPay for WooCommerce plugin (available in the WordPress plugin directory). Enter your API key in the settings and OpPay will appear as a payment option at checkout automatically.

React / Next.js

import { useCallback } from 'react';

export function PayButton({ amount, btc, merchant, description }) {
  const handlePay = useCallback(() => {
    OpPay.open({
      amount, btc, merchant, description,
      currency: 'EUR',
      api_key:  process.env.NEXT_PUBLIC_OPPAY_KEY,
      onSuccess: (d) => router.push(`/order/confirmed?tx=${d.txId}`),
    });
  }, [amount, btc, merchant, description]);

  return <button className="oppay-btn" onClick={handlePay}>₿ Pay</button>;
}

OpPay.open( options )

Opens the payment modal. All options are passed as a single configuration object.

PaymentResult object (onSuccess)

{
  txId:      string,   // Bitcoin transaction hash
  method:    'opnet' | 'btcaddr' | 'opcredit',
  amount:    number,   // amount in chosen currency
  currency:  string,   // ISO currency code
  escrowId?: string,   // only present for OpCredit payments
}

OpPay.close()

Programmatically closes the payment modal. Useful if you need to dismiss it from your own UI logic.

Payment Methods

The OpPay modal always presents all three payment methods. You cannot hide or restrict methods — this ensures the best conversion rate across all customer wallet types.

OPNet Wallet App

The customer scans a QR code with the OPNet mobile app. The transaction is signed offline in the app and broadcast directly to Bitcoin Layer 1. This is the most secure method — the private key never leaves the device and the payment app never connects to your website.

Bitcoin Address

A standard Bitcoin payment address QR is shown. Any Bitcoin wallet (Coinbase, Ledger, BlueWallet, Cash App, etc.) can scan it and send the exact amount. OpPay monitors the mempool for the transaction and confirms it after 1 block. The customer clicks "I've sent the BTC" and OpPay starts watching.

OpCredit — Buy Now Pay Later

See the OpCredit reference section for full details.

OpCredit — Escrow Reference

OpCredit is OpPay's Bitcoin-native buy-now-pay-later system. It uses an OPNet smart contract deployed on Bitcoin Layer 1 to hold funds in escrow between buyer and merchant.

How the escrow works

Escrow identifiers in callbacks

When an OpCredit payment is confirmed, onSuccess fires with method: 'opcredit' and an escrowId like ESC-A3F7C2B1. Store this ID — you will need it to correlate webhook events when the escrow is released or disputed.

Callbacks & Events

OpPay uses three client-side callbacks. For server-side confirmation use webhooks — never trust the client callback alone for order fulfilment.

OpPay.open({
  // ... amount, btc, etc.

  onSuccess: (result) => {
    // Fires on: confirmed payment, escrowed OpCredit, confirmed receipt
    console.log(result.txId);      // Bitcoin tx hash
    console.log(result.method);    // 'opnet' | 'btcaddr' | 'opcredit'
    console.log(result.escrowId);  // only for opcredit
  },

  onFailure: (result) => {
    // Fires on: tx rejected, escrow failed, return requested
    console.log(result.reason);
    // Reasons: 'rejected' | 'escrow_failed' | 'returned' | 'cancelled'
  },

  onCancel: () => {
    // Customer closed modal without completing payment
  },
});

Currency Support

OpPay displays prices in the customer's preferred fiat currency, but every payment settles on-chain in Bitcoin. This means OpPay works for every country in the world — no currency conversion fees, no exchange markup, no blocked regions.

BTC conversion rates are fetched live from CoinGecko at the time OpPay.open() is called. Rates are cached for 60 seconds. We recommend passing a pre-calculated btc amount from your server to ensure accuracy.

Webhooks

OpPay sends a signed HTTP POST to your webhook URL every time a payment event occurs. Configure your webhook URL in the merchant dashboard.

Event types

Webhook payload

{
  "event":      "payment.confirmed",
  "txId":       "0x4a3f2c1d...",
  "amount":     49.99,
  "currency":   "EUR",
  "btc":        0.000495,
  "method":     "btcaddr",
  "merchant_id": "mer_xxxx",
  "session_id":  "sess_xxxx",
  "timestamp":  1710000000,
  "signature":  "sha256=..."
}

Validate the signature header against your webhook secret before processing. Respond with HTTP 200 OK within 5 seconds or OpPay will retry up to 3 times.

Security

API Key Security

Your API key identifies your merchant account. Never expose your live API key in client-side code or public repositories. Use environment variables. For frontend use, use the op_pub_ public key which has read-only scopes.

Bitcoin Address Rotation

For high-volume merchants, we recommend generating a unique Bitcoin address per order via the Sessions API. This enables precise payment matching and prevents any amount confusion. The btc_address and session_id parameters in OpPay.open() support this pattern.

No KYC architecture

OpPay does not collect, store, or process personal data about your customers. There is no customer registration, no ID verification, and no email requirement. The only identifying information is the on-chain Bitcoin transaction, which is public by nature of the Bitcoin protocol.

Fees & Pricing

OpPay has the simplest and lowest pricing in the payment industry.

Frequently Asked Questions

Terms of Service

Last updated: March 1, 2026  ·  Effective: March 1, 2026

• Illegal goods or services of any kind
• Money laundering, terrorist financing, or sanctions evasion
• Fraudulent transactions, fake merchant accounts, or phishing
• High-risk financial products (securities, unregulated financial instruments) without proper licensing
• Adult content in jurisdictions where it is illegal
• Counterfeit goods or trademark infringement
• Multi-level marketing schemes or pyramid schemes
• Proceeds from theft, extortion, or ransomware

Privacy Policy

Last updated: March 1, 2026

• Your merchant name or store name
• Your website URL
• Your Bitcoin receiving address
• An email address (optional — only required for webhook notifications and account recovery)

• The Bitcoin transaction hash (public information on the Bitcoin blockchain)
• The amount and currency of the payment
• A session ID (anonymous, not linked to any personal identity)

• CoinGecko — for live BTC price data (no personal data is shared)
• OPNet infrastructure — for Bitcoin Layer 1 transaction monitoring

Cookie Policy

AML Statement

Anti-Money Laundering & Counter-Terrorism Financing Statement

• Merchant terms of service prohibit use of OpPay for illegal activity, money laundering, or terrorist financing
• Merchant accounts can be suspended if credible reports of illegal activity are received
• We cooperate fully with law enforcement requests supported by valid legal process
• We monitor for merchants operating in prohibited sectors