From WHMCS Documentation

Supported Features

Type One Time Recurring Refunds Reversals
3rd Party Yes Yes Yes



Begin by activating the payment gateway under Setup > Payments > Payment Gateways and choose 2CheckOut from the All Payment Gateways tab.

Once activated, you can then enter the configuration details explained below.

2CO Configuration


2CO Notifications Setup

To setup the callback process for 2CheckOut to automatically mark invoices paid, you will need to login to your 2CheckOut account and click the Notifications tab:

Direct Return

In order to return clients back to your WHMCS installation after a successful payment you can configure Direct Return within the 2CheckOut control panel:

Checkout Style

Two checkout styles are made available as part of 2CheckOut configuration:

  • Inline Checkout - Inline Checkout is an iframe payment option which displays a secure payment form as an overlay when your client is making payment. This allows for payment to be taken from a client without them leaving your site. WHMCS recommends this checkout style when using 2CheckOut.
  • Standard Checkout - Standard Checkout will redirect a client to the 2CheckOut site to make payment before they are redirected back to your site.

Secret Word

For Security, a secret word is set inside your 2CheckOut account, this must be entered into WHMCS for notifications and client redirects to be successful:

  • In your 2Chekcout Account Navigate to Account tab > Site Management
  • Copy the Secret Word displayed towards the bottom of the page.
  • Paste the Secret Word into the Secret Word field of the 2CheckOut configuration within the WHMCS administration.

API Username/Password

2CO API User Setup

If you wish to be able to use the inline, recurring billing and automatic refunds functionality within WHMCS, then you must setup a 2CheckOut API user and enter the details in these fields.

To setup an API user, you will need to login to your 2CheckOut account and go to Account > User Management

  • Click Create Username
  • Enter an email address, username & password, security question & answer.
  • Select the permissions for the user. You just need to select API Access & API Updating for the permissions.
  • Enter the same username & password that you just created into the appropriate API username and API password fields inside WHMCS.

Recurring Billing

This option allows you to choose the options your clients have to pay when viewing an invoice, or going through the checkout process. A recurring payment with 2CheckOut is automatically sent when due without the need for the client to login and pay again. No card details are saved in WHMCS when using 2CheckOut.

Offer Recurring & One Time Payments

Allow the choice to your clients by providing both Recurring and One Time Billing options.

Offer Recurring Only

Only provide a recurring button to your clients. The button will only appear when there is a recurring item on the invoice, and when the invoice is not overdue.

Offer One Time Only

Only provide the option for One Time payments to your clients. No automatic recurring payments will be received.

Skip 2CO Fraud Check

Ticking this option will prevent 2Checkout from performing their fraud checks on payments. It can result in faster processing of payments, but may potentially increase your exposure to fraudulent orders and charge-backs.

Should a payment that has been recorded in WHMCS later be determined to be fraudulent, manual action would be required to reverse the payment recorded in WHMCS and suspend any services as appropriate.

Error Messages

Demo Mode

In order to use demo mode, the "Demo Setting" in your 2CheckOut account should be set to "Parameter" under Account > Site Management. Demo mode can then be enabled by ticking the checkbox in WHMCS under Setup > Payments > Payment Gateways.

Please note that when using demo mode, all callbacks from 2CheckOut will fail with the error MD5 Hash Failure if a secret word is specified. This is done intentionally by 2Checkout to protect those who sell digital goods from fraudulent purchases through their demo mode.

In Demo Mode, valid credit card data must be submitted in order to properly perform the request. Credit cards will not be charged during this process.

MD5 Hash Failure

An MD5 Hash Failure error under Billing > Gateway Log indicates that the Secret Word in Setup > Payments > Payment Gateways does not match the Secret Word in the 2CheckOut control panel. Double check your entry is exactly right, and check for any invisible trailing spaces if so.

Authentication failed

This error in the Gateway Log indicates that either the secret word, API username, or API password are incorrect. These may be reconfigured at Setup > Payments > Payment Gateways. For further information on this configuration see above.

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