WHMCS has two ways to sell more than the base product. Configurable options are choices made during ordering that change the product itself – extra disk space, more RAM, an operating system or a dedicated IP. Product addons are separate extras with their own billing – an SSL certificate, priority support or offsite backups. This guide explains when to use each and how to set them up.
Before you start
- Your base products created; see create products in WHMCS.
- For options that change server resources, check that your server module supports them (VPS modules usually map option names to resources).
Configurable options or addons?
| Configurable options | Product addons | |
|---|---|---|
| Billed | With the product, same cycle | Separately, own cycle possible |
| Good for | Resources, OS choice, locations | Services that can be added or cancelled later |
| Module integration | Passed to the product's module | Optional own module or welcome email |
Create a configurable option group
- Go to Configuration → System Settings → Configurable Options.
- Click Create a New Group, name it (for example
VPS Options) and select the products it applies to. - Click Save Changes, then Add New Configurable Option. A popup opens.
- Enter the Option Name. For module-linked options, use the name the module expects, often in the format
ram|Memory(internal name before the pipe, display name after). - Choose the Option Type:
- Dropdown or Radio – choose one value (e.g. OS, location).
- Yes/No – a checkbox (e.g. dedicated IP).
- Quantity – a number with min and max (e.g. extra GB).
- Add each sub-option with its price per billing cycle. Use 0 for the default choice.
- Save and close the popup.
Customers now see these choices on the product configuration page, and the total updates live.
Create a product addon
- Go to Configuration → System Settings → Product Addons.
- Click Add New Addon.
- Enter the name and description, tick Show on Order and choose the welcome email.
- On the Pricing tab, set a one-time or recurring price and billing cycles.
- On the Module Settings tab, choose a module if the addon should provision something automatically.
- On the Applicable Products tab, select the products it can be added to.
- Click Save Changes.
Upgrades and downgrades
- Clients can change configurable options later from the service page in the client area (Upgrade/Downgrade Options) if you enable Allow Configurable Options Upgrades on the product's Upgrades tab.
- WHMCS calculates a pro-rata invoice and runs the module's change package function after payment.
- Addons can be ordered later from Services → Order New Services → Addons in the client area.
Troubleshooting
- Option not shown in the cart: the group is not linked to the product, or the option has no price in the visitor's currency.
- Server resources do not change: the option's internal name does not match what the module expects. Check the module's documentation.
- Addon ignored by provisioning: no module selected for the addon; handle it manually or attach a module.