Multi Device Retail Platform

I need a developer to create a custom retail platform that feels seamless whether customers visit from a desktop, a mobile phone, or a tablet. Responsive layouts and consistent functionality across those three environments are essential to me. Core requirements • Secure user account management with signup, login, profile editing, and password recovery • Full payment-gateway integration so customers can complete transactions without leaving the site (please indicate the gateways you have worked with) I am open to the tech stack you prefer, provided you can demonstrate past projects with comparable scale and hand over clean, well-documented code. Once built, I will need a short hand-off session or video walkthrough explaining environment setup, deployment steps, and how to extend key modules. Acceptance criteria 1. Interface renders correctly on current versions of Chrome, Safari, Firefox, iOS, and Android. 2. A new user can register, add items to a cart, and complete checkout using a sandbox gateway. 3. Administrator can view user details and transaction logs from a protected back office. 4. Source code builds reproducibly from a fresh clone with instructions you supply. If you have questions or suggestions that could improve scalability or user experience, let me know in your proposal along with relevant portfolio links.