API Development and Payment Gateway Integration for Online Store

Our team helped a well-known company develop a custom backend for their online store. The server-side part provides all necessary functionality and complies with General Data Protection Regulation (GDPR) requirements and recommendations.

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98%

payment success rate

2x

faster checkout completion

45%

reduction in abandoned carts

All Technologies Used

Node.js
Node.js
Rspec
Rspec
Jest
Jest

Motivation

Many users have long appreciated the benefits of online stores, which save time by eliminating trips to shopping centers. Customers can browse products at their own pace, review detailed descriptions, compare prices, and make informed choices. Online stores also help businesses enhance service quality, increase customer loyalty, and provide round-the-clock access to products. The client hired Azati to create a custom store from scratch, including all essential functionality, from direct online payments to order tracking, and later requested integration with a popular payment gateway.

Main Challenges

Challenge 01
GDPR Compliance

The team needed to implement full personal data protection under GDPR, including encryption, secure storage, and compliance with processing standards. Azati addressed this by designing GDPR-ready database structures, encryption protocols, and data access controls.

#1
Challenge 02
Lack of Front-End Designs

Without access to UI mockups, backend endpoints had to be adjusted multiple times to match expected front-end behavior. The team worked closely with the client to iteratively test and align API responses with the interface requirements.

#2
Challenge 03
Custom Development vs Existing Solutions

Off-the-shelf solutions couldn’t accommodate the client’s unique workflows and features, necessitating development from scratch. Azati designed a tailored architecture to integrate order management, product recommendations, and payment processing efficiently.

#3

Our Approach

Agile Methodology
The project followed SCRUM methodology with Jira for task management. The team coordinated feature development, ERP/CRM integrations, and account management to ensure timely delivery.
Custom E-Commerce Features Development
Our team built custom features like order management, invoice generation, and payment gateway integration to match the customer’s specific business needs. This included multi-language support (German/English) and GDPR-compliant data security.
Payment Gateway Integration
We integrated the payment gateway, supporting PayPal, Visa, Mastercard, and American Express, allowing users to securely complete transactions online.
Performance & Security Optimization
Backend performance was optimized to handle high user traffic, and encryption standards were applied for user data, ensuring both speed and security.
Iterative Testing and Deployment
Each feature underwent testing before deployment to production, with continuous monitoring for performance, functionality, and security compliance.

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Solution

01

Navigation & Filtering Module

This module provides a smooth and intuitive shopping experience, allowing customers to quickly browse through product categories, search for specific items, and filter results based on attributes like price, brand, or availability. The system supports multi-language interfaces to cater to a broader audience.
Key capabilities:
  • Fast search and category filtering
  • Product sorting and recommendation support
  • Multi-language interface support
02

Product Management & Order Processing Module

Enables the client to efficiently create, edit, and display product listings while managing orders from purchase to fulfillment. Automated notifications keep customers informed about order status, and the backend ensures accurate inventory tracking.
Key capabilities:
  • Product inventory management and catalog updates
  • Order tracking and fulfillment workflow
  • Automated notifications and status updates
03

Payment & Invoice Module

Handles secure online transactions and generates invoices in multiple formats (PDF, email, HTML) for customer convenience and regulatory compliance. Integration with multiple payment methods ensures flexibility for international users.
Key capabilities:
  • Integration with PayPal, Visa, Mastercard, American Express
  • Automated invoice generation in multiple formats
  • Secure transaction logging and validation
04

Security & GDPR Compliance

Ensures all user and transaction data is encrypted, stored securely, and fully compliant with GDPR requirements. Access controls and audit logs maintain data integrity while enabling regulatory reporting.
Key capabilities:
  • End-to-end encryption of personal and payment data
  • Role-based access control and permissions
  • Audit logging and GDPR-ready storage compliance
05

Reporting & Analytics Module

Provides real-time insights into user behavior, sales, and operational metrics, helping the client make data-driven decisions. The system can track traffic patterns, conversion rates, and payment trends while supporting scalability for growing datasets.
Key capabilities:
  • Real-time dashboards for sales, user activity, and payment stats
  • User engagement and conversion monitoring
  • Performance analytics and operational insights

Business Value

Enhanced Checkout Performance: Checkout speed improved by 30–50%, providing users with a faster and smoother transaction experience.

Increased Order Completion: Order completion rates rose by 25–45%, helping the store convert more visitors into paying customers.

Reduced Payment Errors: Payment errors decreased by 20–35%, improving reliability and user trust in online transactions.

Secure Transactions: GDPR-compliant architecture ensures personal data protection for EU users.

Operational Efficiency: Automation of payment processing, invoice generation, and order management freed internal staff to focus on higher-value tasks.

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