Introduction to One-click Checkout: Build One-click Checkout Extensions for Payment Gateways

Integrating third-party payment gateways into Fynd Commerce checkout involves several challenges. Storefronts often modify the default checkout process to support features such as "Buy Now" functionality, anonymous cart (guest user) checkout, and custom cart validation logic. Payment flows require highly secure, reliable backend logic to prevent fraud, verify payments, and ensure accurate order creation and tracking. Synchronization between backend, payment gateway, and frontend is essential to avoid lost orders, duplicate charges, or poor customer experience. After payment, users must be redirected to the correct success or failure pages with all relevant order details for tracking and feedback.

The diversity of payment providers, each with unique SDKs, APIs, and signature verification methods, requires unified logic and thorough documentation. Ignoring these complexities can lead to payment failures, abandoned carts, and reconciliation issues, harming sales and customer satisfaction.

This documentation provides a comprehensive framework for building One-click checkout flows that integrate smoothly with external payment gateways. It covers client-side code injection to intercept Buy Now or Checkout actions, backend endpoint design for payment initiation and verification, and secure processing of payment callbacks to prevent tampering or duplicate orders.

The documentation also explains how to ensure users are consistently redirected to accurate, trackable order status pages after payment. All recommended practices and code samples are pluggable and provider-agnostic, allowing easy adaptation to various payment gateways. The guide also covers best practices for API security, input validation, and error handling to ensure a reliable, maintainable solution. Following this approach enables you to create a secure, conversion-optimized One-click checkout solution for Fynd Commerce that supports any payment gateway integration.

Quick Start

To get started with building One-click checkout extensions, follow these steps:

1. Start with the Getting Started page to understand the different implementation approaches, framework overview, and prerequisites.
2. Use the End-to-End Framework for consistent implementation across payment providers.

The checkout flow follows a sequential process: script injection intercepts checkout actions and creates the order, the payment handler receives the payment response from the gateway, the verify endpoint processes and validates the payment, and redirection completes the user journey. Each step builds on the previous one and is documented in detail in the following pages.