case study
Nevogate Frontend Audit & Paywall Development
Frontend Audit
Paywall Development
Modernization
Performance
overview
Nevogate
Nevogate is Hungary's largest online payment orchestration platform, with more than 10 years of market experience. Through a single service, it provides access to the most sought-after domestic and international payment providers and payment solutions, enabling every merchant to find the most suitable payment option. Beyond transaction processing, Nevogate supports e-commerce with market-leading value-added services: intelligent payment provider monitoring for maximum availability, automated settlement processing to reduce administration, online invoicing for paperless operations, and provider-independent link and QR code payments for flexible payment options.
Sector
fintech
Services
Frontend Audit
Project-Based Development
Technologies
Frontend
Next.js
React
Square21 delivered a modernized, scalable, and high-performing paywall system for Nevogate — starting with a comprehensive technical audit and culminating in a fully rebuilt frontend aligned with modern best practices. The collaboration ensured that Nevogate now has a reliable, user-friendly, future-proof payment experience that supports their business as it grows.
challenges
Overcoming legacy constraints
Outdated Technology Stack
The paywall frontend was constrained by legacy decisions including Node.js 16, increasing security and compatibility risks.
Maintainability Issues
Heavy use of class components made the code harder to maintain and scale, while overreliance on styled-components led to inconsistent styling and runtime overhead.
Missing Modern Patterns
Lack of modern form validation, state management, and API handling patterns, along with tight coupling between UI and business logic, reduced testability and modularity.
Payment Flow Limitations
Nevogate needed a more flexible, brandable, and reliable paywall that would support multiple payment providers, provide one-click payment options, and handle errors, cancellations, and retries gracefully.
what we changed
Our solutions
1
Frontend Audit & Technical Strategy
We conducted a full codebase review to evaluate architecture, UX flow, maintainability, performance, and developer experience. Our audit reviewed:
Technology stack and architecture (Next.js, TypeScript, SSR/SSG usage)
Styling, theming, and component structure, including dynamic brand themes
Form handling, validation, and API interactions
Error handling, payment flows, retry logic & edge cases
Internationalization, accessibility, and global theming
Code quality, modularity, and consistency
The audit concluded with a detailed technical roadmap recommending upgrading to a modern Next.js version, migrating to TailwindCSS, replacing class components with React functional components & hooks, implementing react-hook-form and zod for validation, introducing React Query for caching, and creating a standalone API SDK.
2
Paywall Development & Modernization
Based on the audit, Square21 implemented a new, modern paywall architecture fully aligned with Nevogate’s technical and product goals:
Repo Upgrade & Setup: Next.js upgrade, migration to TailwindCSS, integration of React Query, react-hook-form, and modern form/validation tools
UI Implementation: Development of responsive desktop and mobile UI with modern, consistent theming aligned with multiple brands
Payment Flows: Full implementation of all payment flows, including multiple payment methods, one-click payments, legal confirmation flows, retry and cancellation logic, and auto-refresh for pending payments
API Integration: Improved state handling, modular and testable business logic separated from UI components, and stronger error and edge-case management
results and impact
See our success stories
Delivered a modern, maintainable codebase with fully upgraded technology stack, reduced complexity, and improved developer productivity.
Achieved faster, more reliable payment flows with smoother transitions, robust error handling, auto-refresh, and one-click payments functioning flawlessly.
Improved performance and scalability with faster page load times, reduced runtime overhead, and better caching with React Query.
Enhanced user experience across brands with fully responsive UI, dynamic theming system, and clearer payment interactions.
"Square21 transformed our existing pre-built checkout interface into a modern, highly scalable, fast, and extremely user-friendly solution. They started with a thorough technical audit and concluded with a complete redesign of the interface, allowing us to offer our customers a reliable, easy-to-manage, and future-proof payment process. Throughout the collaboration, we experienced a flexible and proactive approach – it was clear they love what they do – and they supported high-quality execution with valuable professional suggestions. The result exceeded all our expectations – we highly recommend them."
David Fehér
Business Development Director, Nevogate
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