Custom E-commerce Checkout Flow
We built a standalone application to integrate the NMI payment gateway, bypassing native Shopify checkout limitations for a direct-to-consumer retailer.
Technologies used:
15 Dec 2025
USA
The Vision & Challenge
For direct-to-consumer brands, the Shopify platform offers a reliable foundation for growth. It provides a comprehensive suite of tools for managing products, inventory, and customer data. However, its structured ecosystem can present significant constraints for businesses with specific operational needs.
A promising e-commerce retailer faced a critical barrier. Their business model depended on using the NMI payment gateway, a processor not natively supported by Shopify. This incompatibility was not a minor inconvenience-it was a fundamental obstacle that prevented them from processing any online sales and launching their business.
Our team was brought in to engineer a direct solution. We designed and developed a custom Shopify application that operates outside the native checkout flow. This application provides the specific payment integration the client required while maintaining a cohesive and trustworthy user experience.
Project challenges
- Shopify's checkout process is a closed system. Bypassing it requires creating an entirely separate yet fully integrated application.
- The custom checkout had to replicate essential Shopify logic, including real-time validation for discount codes and accurate, tiered shipping rate calculations.
- Integrating a third-party payment gateway demands a secure, server-side architecture to handle sensitive transaction data correctly.
Solutions
- We built a standalone application using Laravel for the backend and React for the frontend, which intercepts the customer journey before the final payment step.
- Our system connects directly to Shopify's APIs to pull and validate data. This ensures discount codes work as expected and shipping costs are calculated accurately based on the customer's cart and location.
- A server-side integration with the NMI gateway was developed to manage all payment authorizations. This process ensures transaction data remains secure and is never exposed on the client side.
Technologies used
We are concerned about the security and performance of our customers. That's why we always keep updating and use best technologies in our products
Front-end
JavaScript
ReactJS
HTML5
CSS3
Back-end
PHP
Laravel
DevOps
Linux
Digital Ocean
Github CI
Database
MySQL
Independent Payment Processing
The application’s core function is its direct integration with the NMI payment gateway. The Laravel backend securely communicates with NMI’s API to authorize and process transactions. This architecture gave the client the freedom to use their required payment processor, which was the central objective of the project.
Dynamic Checkout Logic
To create a consistent user experience, the application makes real-time API calls to Shopify. When a customer enters an address or a discount code, our system instantly retrieves the correct shipping rates and confirms the code’s validity. This maintains the expected functionality of a native checkout and ensures order totals are always accurate.