Installation Guide
You need an APP ID & APP Secret to complete this guide.
If you don't have them yet, check out our Get Started With Simpler guide.
Installing the Extension
There are two ways to install Simpler Checkout on OpenCart.
Via the admin panel. Log in to your OpenCart admin, go to Extensions > Marketplace, search for "Simpler", open the Simpler Checkout listing, and click Install on the Download tab.
Via manual upload. Download the extension from the OpenCart Marketplace, then in your admin go to Extensions > Installer, click Upload, and select the downloaded file.
Store Credentials
Go to Extensions > Extensions, select Modules, find Simpler Checkout, click the green Install button if it's not already installed, and click Edit to open the configuration page.
The Basic Configuration tab shows a credentials block for each store in your OpenCart installation. For each store you want to connect, enter your APP ID and APP Secret, then check Store Status to enable Simpler for that store.
If you run multiple stores, each store has its own credentials block — configure and enable them individually. Hover over any field's label on the settings page to see an inline description of what it does.
Replace your Native Checkout
When Checkout as a Service (CaaS) is enabled, customers navigating to the checkout page are automatically redirected to Simpler's hosted checkout with their current cart contents — including any applied coupons and product options.
To enable, check Checkout as a Service under the Basic Configuration tab's Features section, and save.
If Test Mode is enabled, only logged-in admin users are redirected to Simpler's hosted checkout. Customers will continue to see the native checkout page. Use this to verify the flow before going live.
CaaS also intercepts third-party "quick checkout" extensions that use the standard extension/quickcheckout/checkout route. No additional configuration is needed.