I am whmcs expert. Please check my profile and complete ratio and repeat hire ratio. I believe in long term relation with client with providing support in all ways.
We have worked in WHMCS since last 5+ years. We are aware about WHMCS internal and external APIs. We have worked with both Linux and Window Hostings. We have already enhanced some functionality based on Internal API in client area. We have already integrated all client areas features in website as listed below:
Display the products in the front website based on group like hosting, reseller hosting, VPS, dedicated server and domain booking.
We have integrated resellerclub API to check domain availability and domain booking.
We have implemented whole cart flow with coupon code in front website with the external APIs like, Check coupon code validity and coupon code apply on particular products, payment gateway integration and place an order.
We have integrate all client area features like Manage Domain, Manage Services, Manage Invoices , Manage Support in front website with external APIs.
We have very well aware about third party modules of resellerclub [ auto sync domain pricing and promos ], namecheap for SSL and all other payment gateways and addition provisional modules.