Requirements and limits

This module has been tested on the platforms below. The latest fresh WHMCS 9.0.8 walkthrough verified Sandbox payments, a 3D Secure challenge, a partial refund and a Resolution Center alert. Card-saving currently has a Sandbox limitation, so confirm a reusable Pay Method before relying on automatic collection.

Tested installations

Other WHMCS 8.x and 9.x releases and other PHP 8.3 point releases are likely to work the same way. Another system theme needs the two payment templates copied into it, covered in Install the module. These three are the ones actually checked.

What your hosting needs

• A public HTTPS address for WHMCS, with the System URL set correctly. Whop needs to reach your installation to confirm payments.
• WHMCS's own cron running, normally every five minutes. It finishes payment updates and keeps billing on schedule.
• Outbound HTTPS access from your server to Whop.

What Whop needs

• A Whop business based in a country Whop supports. Whop excludes only a short list of countries, mostly ones under sanctions; almost everywhere else can host a Whop business.
• An API key with the correct access: 21 permissions selected in Whop.
• A completed verification before you can withdraw money. You can start selling, with a limited set of payment methods, before that is done.

Currencies

The module supports 77 invoice currencies. 68 of them work as soon as you connect. 9 more, CLP, COP, JPY, KRW, MGA, PYG, RWF, VND, XOF, are whole-unit currencies: the Enable whole-unit currencies setting turns them on, off by default, and they only accept whole amounts, no cents. Hungarian forint (HUF) is not supported.

If an invoice is in a currency the module does not support, the invoice still shows up in WHMCS as normal. The payment page just shows a short message instead of the card form or checkout, asking the customer to choose a different payment method.

For example, a 1000 JPY invoice can be paid because it is a whole amount. A 1000.50 JPY balance cannot, until it is adjusted to a whole number, because whole-unit currencies never accept a balance with decimals.

Payment methods

Use public test cards for safe Sandbox validation. Sandbox can display other payment choices too; a visible option is not proof that its full test flow is supported. Live shows the methods enabled for that buyer, amount, and currency. Apple Pay and Google Pay need a public HTTPS address (no localhost) and the usual wallet eligibility on the buyer's side; neither works in Sandbox. Check the business’s current checkout limit in Whop and request a review if needed; see Paying an invoice.

What it does not do

• It does not import saved cards or subscriptions from another payment gateway.
• Whop Checkout does not save a card or collect automatic renewals.
• There are no Whop subscriptions. WHMCS creates every renewal invoice, and each Whop payment pays one of them.
• Disputes are handled inside Whop, not inside WHMCS.
• A 3D Secure choice is a request, not a guarantee. The card issuer decides whether a challenge actually appears.

Next: Install the module