We need a WordPress tool to accept one-off payments and limited-duration payment plans.

The site owner needed to launch an online payment solution that allowed them to send simple links to clients to pay for services rendered. We could not use a standard shopping cart, since the amount due is not fixed and payment plans are negotiated per client.

The client needed to accept the two different types of payment structure: a one-time payment and a multiple-installment repayment over time with a user-defined amount and repayment schedule. The client had selected the pro version of an existing WordPress plugin, WP Simple Pay. It performed great great except it did not explicitly support our concept of dynamic installment plans.

I wrote JavaScript that leveraged the hash in the URL to pre-populate the payment forms instead of relying on the user to set up the proper payment scenarios. This allowed the client to easily generate payment links to send to their users. A simple WordPress shortcode on the subscription page injects all the JavaScript and site logic required to upgrade the native functionality of the plugin to support the client's specific needs.