<![CDATA[The inefficient product promotion system and the limited reach of product catalog marketing to prospective customers have caused the UD Invitation Card printing industry to not achieve maximum turnover. Total Graphics. This paper aims to present a multi-platform e-commerce application model that is used for product catalog promotion, ordering and tracking of product delivery orders for invitation card printing for customers. Web-based multi-platform system on the administrator side and mobile-based on the customer side, developed following the stages in the Prototyping-Based development model. The system design uses object-oriented tools, built using the PHP programming language with the Laravel framework, and a PostgreeSQL database. The functional features of the application system are tested using Blackbox testing techniques. The test results show that all functional features contained in the application, especially the function of delivering product catalog information, product ordering functions, and order delivery tracking functions are functioning validly.Keywords: Promotion of goods; E-commerce; Web-based; Mobile based; Prototyping Abstrak. Kurang efisiennya sistem promosi produk dan terbatasnya jangkauan pemasaran katalog produk kepada calon pelanggan, menyebabkan tidak tercapainya omset secara maksimal pada industri percetakan Kartu Undangan UD. Total Graphics. Paper ini bertujuan menyajikan model aplikasi e-commerce multi platform yang digunakan untuk promosi katalog produk, pemesanan dan tracking pengiriman produk pesanan percetakan kartu undangan bagi pelanggan. Sistem multi platform berbasis web pada sisi administrator dan berbasis mobile pada sisi pelanggan, dikembangkan mengikuti tahapan-tahapan dalam model pengembangan Berbasis Prototyping. Desain sistem menggunakan tools berorientasi objek, dibangun menggunakan bahasa pemrograman PHP dengan framework Laravel, dan database PostgreeSQL. Fitur-fitur fungsional sistem aplikasi diuji dengan teknik pengujian Blackbox. Hasil pengujian menunjukkan seluruh fitur fungsional yang terdapat pada aplikasi, terutama fungsi penyampaian informasi katalog produk, fungsi pemesanan produk, serta fungsi tracking pengiriman pesanan berfungsi secara valid. Kata kunci: Promosi barang; E-commerce; Berbasis web; Berbasis mobile; Prototyping]]>
