Solana Pay for WooCommerce: accept USDC and mark orders paid automatically

WooCommerce has no built-in Solana Pay gateway. You don't need a heavy plugin, though: an offline payment method, a thank-you page hook and a small verifier are enough.

1. How it works

1. Customer checks out with an offline method renamed "Solana Pay (USDC)". The order goes on hold.
2. The thank-you page shows a Solana Pay URL: solana:<your address>?amount=<order total>&spl-token=EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v&reference=<unique key>, as a QR code.
3. A verifier looks up transactions that include the reference key and checks that your USDC balance rose by at least the order total.
4. When it confirms, call $order->payment_complete($signature).

2. The thank-you hook

add_action('woocommerce_thankyou', function ($order_id) {
  $order = wc_get_order($order_id);
  if ($order->is_paid()) return;
  // 1) create + store a reference on the order (_solpay_ref)
  // 2) build the solana: URL with the order total
  // 3) render a QR and poll an AJAX endpoint
});

3. Verify on the server, never in the browser

Your AJAX handler should check the order key, call the verifier with the server-side order total, and only then mark the order paid. Use getSignaturesForAddress(reference), then getTransaction with jsonParsed, and compare preTokenBalances with postTokenBalances for your address and the USDC mint.

4. Gotchas

• Use a fresh reference per order and never reuse it.
• Use a reliable RPC, because public RPCs rate-limit.
• USDC needs a token account on your wallet. Wallets create it on the first receive, or you can create it ahead of time.
• Round totals to 6 decimals or fewer.

The Pro Kit ships this as a ready PHP plugin file plus the matching /api/ref and /api/verify-amount worker routes.

Payments are on-chain and final; if delivery fails, email smallbizaicourses@gmail.com with your order reference. Software provided as is. Not financial advice.