Hire the Best Payment Gateway Integration Specialists
in Ukraine

Payment bugs and failed webhooks cost you real revenue. I build and fix payment flows that reconcile to the cent: Stripe integrations, subscriptions and billing, invoicing, card processing, bank APIs. 10+ years of backend engineering (Node.js, TypeScript, PostgreSQL), currently a team lead at a fintech company processing millions of transactions. $100K+ earned on Upwork, 100% Job Success, including two 6-year contracts with the same clients Senior full-stack engineer with $100K+ earned on Upwork, 4,300+ hours, and a 100% Job Success Score. I ship and stabilize production web systems—from urgent Vue/Nuxt/React frontend work to Node.js APIs, PostgreSQL, payment flows, and AI integrations. I’m a strong fit when you need: • a production bug fixed without destabilizing an existing codebase • a responsive landing page or frontend implemented from Figma • a Node.js/TypeScript API or third-party integration • payment, transaction, invoicing, or fintech business logic • an n8n or OpenAI/Claude workflow engineered with retries, validation, and safe failure handling My Upwork history includes long-running full-stack products, complex frontend animation, and quick delivery on focused frontend tasks. Clients have specifically highlighted speed, reliability, and the ability to get difficult UI work right the first time. Core stack: Node.js, TypeScript, JavaScript, PostgreSQL, Vue.js, Nuxt, React, NestJS, REST APIs, Docker, payment integrations, n8n, and OpenAI/Claude APIs. Send me the current codebase, design, or production issue, and I’ll give you a direct assessment of the solution, risks, and realistic delivery time.

I build complex WordPress and WooCommerce platforms that go far beyond basic theme setup. My focus is custom WordPress development, WooCommerce architecture, custom plugins, API integrations, Stripe payments, ERP integrations, booking systems, e-learning platforms, AI-powered features, and internal workflow automation. I can help you with: • Custom WooCommerce stores and large product catalogs • WooCommerce checkout, payment, delivery, and order logic • Stripe, Apple Pay, Google Pay, and custom payment flows • Custom WordPress plugin development • ACF-based WordPress architecture • REST API integrations with third-party services • ERP, delivery, marketplace, and CRM integrations • Custom admin panels and internal workflow automation • Booking systems, user dashboards, and client portals • E-learning platforms and subscription-based platforms • AI-powered search, translation, and automation features • REST APIs for mobile apps and external websites • Performance optimization and production fixes Recent WordPress projects I worked on include: • A WooCommerce store with 5,000+ SKUs, payment integrations, delivery APIs, ERP sync, B2B automation, marketplace synchronization, and AI-powered product search • A custom WordPress learning platform with user accounts, lesson scheduling, Stripe subscriptions, custom admin tools, AI translations, text-to-speech, pronunciation scoring, video lesson integrations, and mobile API • A custom booking platform with Stripe payments, flight tracking, holiday-based pricing logic, user dashboard, admin management tools, and external API for connecting other websites My core stack includes WordPress, WooCommerce, PHP, ACF, JavaScript, REST API, Stripe, PostgreSQL, MySQL, React, Next.js, Node.js, Cloudflare, Vercel, and Linux-based deployment environments. What makes me different is that I do not just install themes and plugins. I build custom business logic, integrations, admin workflows, and production-ready systems that are stable, maintainable, and designed for real operations. I can take ownership of the full development process: planning, architecture, backend logic, frontend implementation, API integrations, testing, deployment, and post-launch fixes. If you need a WordPress/WooCommerce developer who can handle complex functionality, custom integrations, and production-level development, I can help you build it properly.

🚀 Hi, I'm Dmytro, I'm a Full Stack Developer AI with more than 8 years of experience building SaaS platforms, AI-powered applications, and scalable web products for startups, product companies, and growing businesses. As a Full Stack Developer AI, I've worked on MVPs, enterprise platforms, automation tools, and intelligent web applications used by thousands of users worldwide. 💡 My primary focus as a Full Stack Developer AI is designing complete software solutions that combine modern frontend technologies, scalable backend architecture, and artificial intelligence. As a Python Full Stack Developer, I enjoy transforming complex business requirements into reliable, maintainable, and high-performing products that deliver measurable business value. 🤝 Throughout my career as a Full Stack Developer AI, I've collaborated with designers, product managers, AI engineers, DevOps specialists, and business stakeholders. I believe every SaaS Developer should understand not only software architecture but also customer needs, product strategy, and long-term scalability. 🛠️ Technologies I work with As a Python Full Stack Developer, my primary stack includes: • Python • Django • Flask • FastAPI • React • Next.js • TypeScript • JavaScript • Node.js • PostgreSQL • MongoDB • Redis • Docker • AWS • OpenAI API • LangChain 📈 Over the years, I've helped companies hire a Full Stack Developer AI capable of building production-ready SaaS platforms, integrating AI into existing products, and modernizing legacy systems. As a SaaS Developer, I focus on creating software that remains scalable as businesses grow. ⚙️ What I can help with As a Full Stack Developer AI, I can help with: • Building AI-powered SaaS platforms from scratch • Developing scalable web applications • Backend architecture and API development • AI integration using OpenAI and LLMs • Workflow automation and intelligent assistants • SaaS architecture and multi-tenant systems • Database design and optimization • Authentication and authorization • Payment gateway integration • Cloud deployment and CI/CD • Performance optimization • Legacy system modernization • Bug fixing and long-term maintenance 🔧 Many companies choose me as a Python Full Stack Developer because I can take ownership of the complete product lifecycle—from architecture and backend development to frontend implementation and AI integration. As a SaaS Developer, I always balance technical quality with business objectives. 🌐 I've worked as a Full Stack Developer AI on startup MVPs, enterprise platforms, internal business systems, CRM solutions, marketplaces, analytics dashboards, and AI automation platforms. My experience as a Python Full Stack Developer allows me to quickly adapt to different domains, engineering processes, and development teams. 🧩 Beyond application development, I have strong experience designing scalable backend systems, cloud infrastructure, and AI services. This enables me to work not only as a Full Stack Developer AI, but also as a technical partner capable of making architectural decisions that support long-term product growth. 💻 I've worked with: • PostgreSQL • MySQL • MongoDB • Redis • Supabase • Firebase • AWS • Docker • Kubernetes • Python • Node.js • React • OpenAI API • LangChain 🔗 This broad technical background allows me to deliver complete products as a Python Full Stack Developer, while my experience as a SaaS Developer helps businesses build reliable platforms that are secure, maintainable, and ready to scale. 🎯 How I work I believe a great Full Stack Developer AI should think beyond writing code. Understanding product strategy, user experience, software architecture, AI capabilities, scalability, and maintainability is equally important. 🤝 As a Python Full Stack Developer, I value ownership, transparency, and close communication with clients. Every SaaS Developer should build software that is easy to extend, simple to maintain, and capable of supporting future business growth. 📚 I've also contributed in areas such as: • Software architecture • AI solution design • Technical planning • Code reviews • Database optimization • CI/CD pipelines • Agile development • Team collaboration • Mentoring developers 🚀 Whether you need a Full Stack Developer AI for a new AI-powered product, a Python Full Stack Developer to strengthen your engineering team, or a SaaS Developer to build a scalable cloud platform, I'd be happy to help. My goal is to deliver software that combines modern engineering practices, artificial intelligence, and business value. 📊 Companies often hire a Full Stack Developer AI to build intelligent SaaS platforms, automate business workflows, or integrate generative AI into existing products. Others look for an experienced Python Full Stack Developer to modernise legacy systems. ✨ If you're looking for a Full Stack Developer AI, I'd be happy to discuss your project. Best regards, Dmytro

Hi, I'm Alex - a Senior WordPress/WooCommerce Developer specializing in peptide and research-compound eCommerce stores. I build, rebuild, and optimize peptide stores end-to-end: design, WooCommerce setup, high-risk payment gateway integration, and — as part of every build — WordPress Speed Optimization to hit 98–100% PageSpeed Insights scores and pass Core Web Vitals. Slow WordPress sites lose visitors, hurt SEO, and cost you money — and peptide stores are especially vulnerable, with heavy catalogs, compliance widgets, COA/lab-result pages, and high-risk gateway scripts all stacking up. Even with WP Rocket, fast hosting, and optimization plugins, many sites still underperform. That's where my expertise in WordPress JavaScript optimization, performance tuning, and real-world Core Web Vitals fixes comes in — built into how I build every peptide store from the ground up, and applied to any WordPress/WooCommerce project that needs it. 🚀 What I Do Peptide eCommerce (my core focus) ✔ Full WooCommerce builds for peptide & research-compound brands ✔ High-Risk Payment Gateway integration (Authorize.net, NMI, and other high-risk processors) ✔ Multilingual / WPML builds for international peptide brands ✔ Compliance-aware UX (age-gate, disclaimers, COA pages) without sacrificing speed WordPress Speed Optimization (for any WP/WooCommerce site) ✔ WordPress Speed Optimization — reduce load times, optimize WordPress JavaScript, improve mobile and desktop performance ✔ Core Web Vitals Optimization — LCP, CLS, INP fixes aligned with Google ranking factors ✔ PageSpeed Expert Audits — deep performance analysis using GTmetrix, PageSpeed Insights, and Google Search Console ✔ WP Rocket Configuration — advanced caching, CSS/JS optimization, lazy loading (configured to not break checkout, gateway, or compliance scripts) ✔ Mobile Speed Optimization — mobile-first Core Web Vitals improvements ✔ WordPress SEO Performance Optimization — speed-focused SEO enhancements ✔ eCommerce Speed Optimization — WooCommerce performance tuning for high-SKU catalogs ✔ Elementor Speed Optimization — reduce builder bloat and improve rendering ✔ Hosting & CDN Optimization — Cloudflare, SiteGround, server-level tuning ✔ Ongoing Speed Maintenance — continuous monitoring and optimization 🛠 My Approach as a PageSpeed Expert 1️⃣ Performance Audit — full audit using GTmetrix, PageSpeed Insights, and Google Search Console 2️⃣ Technical Optimization — WP Rocket, caching, database cleanup, image optimization, CDN setup 3️⃣ Core Web Vitals Fixes — real improvements for mobile and desktop 4️⃣ Testing & Validation — before/after testing with industry tools 5️⃣ Documentation & Handoff — clear report and recommendations I work with all types of WordPress projects: peptide & research-compound stores, WooCommerce stores in general, blogs, SaaS landing pages, agency websites, Elementor builds, and membership platforms — wherever performance, conversions, and SEO are critical. 📊 Results Clients Get 95–100% PageSpeed Insights scores Major Core Web Vitals improvements Faster load times (often 2–5 seconds faster) Better WordPress SEO and Google rankings Higher conversions and lower bounce rates Stable, scalable peptide stores that don't break under high-risk gateway or compliance requirements 🔧 Tech Stack & Keywords WordPress Speed Optimization | PageSpeed Expert | WP Rocket | Core Web Vitals | Google Search Console | WordPress JavaScript | WordPress SEO | GTmetrix | Mobile Optimization | Elementor Performance | WooCommerce Speed | Cloudflare | SiteGround | PHP | CSS/JS Optimization | Lazy Loading | CDN | Peptide eCommerce | High-Risk Payment Gateway | WPML ✔ Top Rated Plus WordPress & PageSpeed Expert ✔ 12+ years WordPress development experience ✔ 200+ WordPress sites optimized, including peptide & high-risk eCommerce stores ✔ Trusted by agencies, SaaS companies, and peptide/eCommerce brands If your WordPress or peptide store is slow — even with WP Rocket and good hosting — I'll fix it with real, data-backed optimizations. As someone deeply focused on peptide eCommerce and WordPress Speed Optimization, I work not just as a PageSpeed Expert, but also as a hands-on WordPress/WooCommerce Developer who understands how performance, code quality, high-risk payment flows, and real-world business goals connect — ensuring every build and every speed improvement is stable, measurable, and scalable. Ready to build or speed up your peptide store — or any WordPress site? Let's talk 🚀

I'm Paul — a WooCommerce engineer and technical architect. I scaled a health startup from $0 to $80M in annual revenue, maintain WooCommerce platforms doing $2M+/month, and helped one store grow revenue 60% in a single year. Over 10+ years I've learned that growth is usually a technical problem in disguise — the store that can't scale is almost always held back by infrastructure that was never built to. Most of my clients aren't looking for a freelancer to knock out a task. They need someone who can see the whole picture — the architecture, the integrations, the team, the roadmap — and make good decisions across all of it. That's the role I step into: a technical partner accountable for outcomes, not just tickets. WooCommerce is usually where the conversation starts. Custom checkout flows, subscription systems, complex pricing logic, and performance that holds under load are table stakes for me. The higher-leverage work is usually the layer underneath: internal tools, automation pipelines, bespoke business logic, and custom engineering that doesn't fit into a plugin. What I actually work on: — WooCommerce architecture, custom plugin development, and platform builds well beyond off-the-shelf solutions. For high-traffic stores, the right call is sometimes moving critical logic — inventory, pricing, order processing — out of WordPress entirely and into dedicated NestJS microservices. WooCommerce stays the storefront; the heavy lifting happens elsewhere. — Performance engineering: not just PageSpeed scores, but the database queries, caching strategy, and infrastructure decisions that keep a platform fast and resilient at scale — the difference between a store that converts and one that buckles on its biggest day. — Internal systems and business automation: tools your team actually uses, workflows that remove manual overhead, integrations that connect your stack. — Technical leadership: stepping in as a de facto CTO or architect, leading dev teams, reviewing code, and keeping complex projects on track. — AI-powered features where they add real leverage — built into the product where it genuinely moves the needle, not as a buzzword. A recent example: a venture-backed infrastructure company — one running a large real-time network of thousands of connected devices across North America — came to me because, for all their scale and funding, they hadn't found a team that could reliably own their server infrastructure. I stabilized their platform under sustained real-time load (100+ concurrent users) where it had been faltering, so the operation kept running instead of buckling as they grew. That's the pattern in most of my work: the business is ready to scale, and the infrastructure is what's holding it back. My stack: PHP, JavaScript, React, Node.js, NestJS, and the full WooCommerce/WordPress ecosystem — plus whatever the problem actually calls for. I work with a small number of clients at a time. If you're building something that needs to last, and you want a technical partner who's done this before at scale — let's talk.

I help startups and growing businesses design, build, and scale 🚀 SaaS products, 🏪 marketplaces, 🛒 ecommerce platforms, 📱 mobile applications, and 💳 subscription-based businesses. With 10+ years of experience as a 💻 Full Stack Developer, 🏗️ Solution Architect, and 👨‍💼 Technical Lead, I deliver scalable products from MVP to production. My expertise covers SaaS development, marketplace platforms, subscription billing systems, payment infrastructure, API integrations, cloud-based applications, and business-critical payment flows. I don't just implement features — I help companies make technical decisions, define architecture, optimize billing processes, integrate payment systems, and launch products faster. ⚡ 🎯 Core Expertise ✅ Full Stack Development • ✅ SaaS Development • ✅ Marketplace Development • ✅ Ecommerce Development • ✅ Subscription Platforms • ✅ Subscription Billing • ✅ Payment Gateway Integration • ✅ Stripe Integration • ✅ PayPal Integration • ✅ Checkout Development • ✅ API Integration • ✅ Mobile App Development • ✅ React Development • ✅ Flutter Development • ✅ Firebase Development • ✅ Supabase Development • ✅ Technical Product Ownership • ✅ Solution Architecture 💳 Payment & Billing Expertise I specialize in building and optimizing payment systems for SaaS businesses, marketplaces, ecommerce stores, and mobile applications. 💰 Stripe Checkout • Stripe Elements • Stripe Payment Element • Stripe Billing • Stripe Subscriptions • Stripe Connect • Stripe Webhooks • Stripe Customer Portal • Stripe Payment Intents • Stripe Setup Intents • Stripe Invoicing • Stripe Tax • Stripe Payment Links • Stripe Radar • Stripe Identity • Stripe Connect Marketplace • Stripe Connect Payouts • Stripe Webhook Development • Stripe Webhook Troubleshooting • Stripe API Integration • Stripe Billing Automation • Stripe Subscription Management • Stripe Subscription Lifecycle Management • Stripe Checkout Optimization • Stripe Checkout Customization • Stripe Recurring Billing • Stripe SaaS Billing • Stripe Marketplace Payments • Stripe Vendor Payouts • Stripe Multi-Currency Payments • Stripe Upgrade & Downgrade Flows • Stripe Trial Management • Stripe Revenue Optimization • Stripe Fraud Prevention • Stripe Payment Security • Stripe Migration 💸 PayPal Integration • PayPal Checkout • PayPal API Integration • PayPal Subscriptions • PayPal Recurring Payments • PayPal Webhooks • PayPal Billing Agreements • PayPal Marketplace Payments 🔗 Payment Gateway Integration • Subscription Billing • Recurring Payments • Billing Automation • Customer Portal • Upgrade & Downgrade Flows • Trial Management • Multi-Currency Payments • Vendor Payouts • Marketplace Payments • Refund Automation • Payment Infrastructure 🚀 SaaS & Product Development I have extensive experience building SaaS platforms and subscription-based products. ☁️ SaaS MVP Development • SaaS Architecture • Multi-Tenant SaaS Applications • B2B SaaS Platforms • B2C SaaS Platforms • AI SaaS Products • SaaS Billing Systems • SaaS Payment Infrastructure • SaaS Subscription Management • SaaS Analytics & Reporting • SaaS Integrations • SaaS Scaling & Performance Optimization • SaaS Checkout Optimization • SaaS Revenue Optimization • Mobile SaaS Applications • SaaS Marketplace Platforms 🏪 Marketplace Expertise I help businesses build and scale marketplace platforms with automated payments and vendor management. 💳 Stripe Connect • Marketplace Payments • Vendor Payouts • Commission Systems • Multi-Vendor Platforms • Booking Platforms • Service Marketplaces • Product Marketplaces • Creator Platforms • Marketplace Billing Systems • Marketplace Checkout Flows • Marketplace Revenue Models 🧠 Technical Product Ownership I often work as a technical partner helping founders and business owners turn ideas into scalable products. 🏗️ Technical Product Ownership • Product Architecture Design • MVP Planning & Development • Startup Product Development • Technical Leadership • Solution Architecture • System Design • Product Roadmap Execution • Platform Scaling • Development Team Leadership • Business Requirements Analysis • Third-Party Integrations • Payment Infrastructure Design • SaaS Architecture Consulting 🛠️ Technologies Backend: PHP • Laravel • MySQL • Redis • Elasticsearch • Apache Solr Frontend: JavaScript • React • Vue.js Mobile: Flutter Backend as a Service: Firebase • Supabase Cloud & Infrastructure: AWS • S3 • CloudFront • Lambda • Docker 📈 Recent Project Experience 🚀 SaaS Billing & Subscription Platforms: Subscription Billing • Stripe Billing • Stripe Subscriptions • Checkout Optimization • Payment Gateway Integration • Recurring Billing • Subscription Lifecycle Management • Revenue Optimization 🏪 Marketplace Solutions: Stripe Connect • Marketplace Payments • Vendor Payouts • Commission Systems • Payment Infrastructure • Multi-Vendor Platforms 🛒 Ecommerce Platforms: Shopify Integrations • WooCommerce Integrations • Stripe Payments • PayPal Payments