Simle Payment Gateway via Karbo masternodes' Decentralized API
It can check payment via any Karbo masternode starting of version v.1.5.8.
Required JSON RPC methods: get_transaction_hashes_by_payment_id and check_tx_with_view_key.
Just open page in browser and enter your public address, private view key, masternode URL and so on in Settings.
Enter or generate Payment ID, amount and create Payment Request. Show QR code to payer or copy payment URI and send it to him.
Gateway uses Payment ID to search for transactions, therefore without it payment will not be confirmed.