Przelewy24 & BLIK Payments for OpenCart — bank transfer, card and BLIK payments in Poland

Przelewy24 & BLIK Payments for OpenCart is a payment module for the Polish market. The buyer pays by bank transfer, card or BLIK through Przelewy24, and the order in your shop is confirmed by itself. The module runs on the Przelewy24 REST API v1 and takes neither the buyer’s return nor a notification at face value: a payment counts only after the signature check and a transaction/verify call, exactly as Przelewy24 requires. Three builds — for OpenCart 4.x, 3.x and 2.3.

What you need. A Przelewy24 merchant account — Przelewy24 issues the merchant ID, CRC key and API key after you register the shop. The order currency is PLN, or EUR and other currencies if your account accepts them. The BLIK code right at checkout (Pro) works only if Przelewy24 has enabled this service on your account; otherwise BLIK goes through the Przelewy24 page. The module follows the official Przelewy24 REST API specification and was tested on test shops against a simulation of the Przelewy24 responses — we recommend making your first payment in the sandbox of your account.

What the buyer sees

Without Pro, after confirming the order the buyer goes to the Przelewy24 page, picks a bank, a card or BLIK and comes back to the shop. Card and bank details never pass through your site. If the buyer closes the tab and never comes back, the order still becomes paid — from the Przelewy24 notification.

The return page from Przelewy24 does not start OpenCart, so the buyer keeps the session even with strict cookie settings (SameSite=Strict on OpenCart 4). As soon as Przelewy24 confirms the payment, the buyer sees the usual “Your order has been placed” page with an empty cart.

What the admin gets

• Merchant ID, POS ID, CRC key and API key — everything you need to start. Where to find them in the Przelewy24 panel is explained right under the fields.
• Sandbox with its own keys. One switch moves the shop to the Przelewy24 sandbox; no real money moves there.
• “Check connection” — the module calls Przelewy24 with your keys and tells you whether they are accepted. You see a wrong key in the admin, not from a buyer.
• The notification URL is sent to Przelewy24 with every payment — nothing to paste in the Przelewy24 panel.
• Methods on the Przelewy24 page (cards, transfers, BLIK, instalments, wallets), payment page language, time to pay and the “wait for the result” mode — your choice.
• Statuses: awaiting payment, paid, needs review, refunded in full. Plus a geo zone and sort order.
• Order history: the Przelewy24 transaction number, amount, refunds, a warning about a second payment or an amount mismatch.
• Debug log: codes and signatures are masked.

How it works — step by step

1. At checkout the buyer chooses Przelewy24. With Pro and BLIK switched on, they type the 6-digit BLIK code right at checkout or click “Other methods” for a transfer or a card. Works on the standard checkout and in One Page Checkout.
2. The module registers the transaction with Przelewy24 (transaction/register) with a unique session number, the order amount and currency, and a SHA-384 signature on the CRC key. The amount is the “Total” row — with coupons, shipping and product options.
3. The buyer pays on the Przelewy24 page. For the BLIK code at checkout (Pro) the module passes the code to Przelewy24 (paymentMethod/blik/chargeByCode), and the buyer confirms the payment in the banking app.
4. The notification arrives at the shop. The module checks the SHA-384 signature and the amount. Faking a payment by sending a POST to the site does not work — such a request is refused.
5. Confirmation. The module calls transaction/verify — without it Przelewy24 does not settle the money to the merchant. Only after a successful verify does the order become paid.
6. The buyer’s return is not proof of payment. The waiting page asks Przelewy24 for the status itself and moves on to “Your order has been placed” once the payment is confirmed.
7. Amount check. If the amount paid differs from the order, the module does not confirm the payment and sets the “needs review” status with an explanation in the history.
8. Cancellation. A buyer who cancelled sees “I have paid” and “Try to pay again”. A new attempt gets a new session; a late payment for the old attempt is not lost either.
9. With Pro you can refund from the payment journal (transaction/refund) — in full or in parts; the result from Przelewy24 is written to the order history.

How much it costs

UAH 990 — a one-time payment, lifetime licence. No yearly fees: the module and its Pro features stay yours. One licence covers all three builds — OpenCart 4.x, 3.x and 2.3.

One key — one domain. Moving the shop? Release the licence on the old domain with the button in the module settings and activate it on the new one.

Trial first, then payment. The free 7-day Pro trial starts from the “Try Pro” button in the module settings with just an e-mail, no card needed. A fresh install is the plain Free version, nothing switches on by itself. After the trial only the Pro features stop; taking payments keeps working.

Under the hood

• The signature is really checked. SHA-384 over the notification fields and your CRC key, plus the amount has to match the order session. An unsigned or foreign notification is rejected, a repeated one changes nothing.
• transaction/verify is mandatory. The order is not paid until Przelewy24 confirms verify.
• Every attempt is its own Przelewy24 session. If the buyer pays an old attempt after a new one, the module finds it too; a second payment for an already paid order is flagged in the history so a manager can refund one of them.
• OpenCart 4: a retry pays the same order. OpenCart 3 and 2.3: the order shows up in the list only after Przelewy24 confirms it, so abandoned attempts do not clutter the admin.
• Own tables for sessions and refunds. They are kept on purpose when the module is uninstalled — the journal and refunds are there after a reinstall.
• The CRC key and API key are stored encrypted (AES-256 + HMAC) and never reach the log.
• No core edits and no OCMOD modifications: a regular OpenCart payment extension.
• A Pro gate that never bricks the shop: when the trial ends, only the Pro features stop, taking payments keeps working.

How to install

1. OpenCart 4: Extensions → Installer → upload cc_przelewy.ocmod.zip (do not rename the archive) and click “Install”. OpenCart 3: Extensions → Installer → cc_przelewy24-oc3.ocmod.zip. OpenCart 2.3: copy the contents of the upload/ folder from cc_przelewy24-oc23.ocmod.zip to the shop root (FTP or the hosting file manager).
2. Extensions → Extensions → Payments → Przelewy24 + BLIK (CatCode) → “Install”, then “Edit”.
3. Switch on Sandbox, enter the merchant ID and the keys of the sandbox account, save and click “Check connection”.
4. Add the PLN currency to the shop (if it is not there yet) and place a test order in the sandbox.
5. Enter the live keys and switch Sandbox off.
6. For Pro: “Try Pro” → an e-mail for the trial or the key after purchase. Switch on “BLIK code at checkout” once Przelewy24 enables the BLIK code service.