Hire the Best PayPal Integration Specialists in Kyiv, UA

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'm a certified FileMaker developer with over 12 years of experience. During these years, I have created many applications on the FileMaker platform. These programs were mostly developed for the iPhone, iPad, Mac desktop, Windows desktop, and WebDirect simultaneously. I have also created multiuser applications for Filemaker Cloud / Filemaker Cloud for AWS. Some of these applications are published in Claris Marketplace. What I offer: - Developing Filemaker applications for any supported devices and services (Filemaker Pro, Filemaker Go, Filemaker Server, Filemaker Cloud) from idea to the finished application - Upgrading an existing client's applications - Prepare existing Filemaker application to the Claris Marketplace compliance - Integrating applications with other services via API - Full post-development support In my projects, I use: - Flexible UI/UX - Custom HTML/JS charts (C3/D3/Google charts), Filemaker native charts - Connection to external data sources: MySQL, PostgreSQL - Import data into Filemaker from external sources (XML, CSV, etc.) - Integrating with third-party services: DocuSign, Twilio, SendGrid, MailChimp, MS services, Google services, etc. - Filemaker REST API, JSON Also, I have extensive experience of over 5 years in developing (developing and programming) devices based on Arduino, ESP8266, and integrating them with Filemaker solutions. And I have a lot of experience as a System administrator / IT manager with experience of over 20 years. I will be glad to discuss your future needs and how I can help you with this.

PHP/Symfony backend developer. 10+ years of experience. I work with payments, APIs, and e-commerce systems. I read unfamiliar code fast, debug well, and write clean code with tests. Code reviewer for 4+ years - I catch problems before they reach production. Stack: PHP 8, Symfony, MySQL, Redis, Memcached, Python, Docker. I use AI tools daily (Claude Code, Copilot). For 6 years I was part of a payments team (~6 people) building a white-label subscription platform - 50+ sites on one codebase. As part of that team I worked on: → Payment integrations: SEPA, card processing, Apple iTunes in-app purchases → Recurring billing: retry logic, rebill scheduling, refunds → REST APIs: internal and third-party integrations → Background jobs: crons, queues, data migrations → Per-site config: payment methods, offers, cross-sells, compliance flows Available 20-40 hrs/week. Looking for long-term hourly work. Open to: backend tasks, API integrations, payment features, general PHP/Symfony work. Let's talk.

I'm a full-stack WordPress developer with 11 years of experience building and maintaining production sites for businesses that can't afford downtime or slow load times. 💻 My work spans: 🏗️ WordPress & Gutenberg Development Custom themes, blocks, and plugin architecture, built for teams that need to actually maintain the site afterward. 🛒 WooCommerce Checkout flows, payment gateway integration (PayPal, Stripe), subscription logic, and database structure (HPOS vs. legacy) for stores handling real transaction volume. ⚡ Performance Optimization I've taken sites from failing PageSpeed audits to fast, Core Web Vitals-passing builds by fixing the actual bottlenecks: render-blocking scripts, duplicate tag loading, unoptimized assets—not just installing a caching plugin and hoping. 🌍 Multilingual & Compliance WPML setups across 5+ languages, GDPR/CCPA cookie consent implementation. 🤖 AI-Powered Development & Automation Integrating AI tools into WordPress workflows and client products, building automation that removes manual work from day-to-day operations. 🔗 JavaScript & Integrations Custom front-end logic, API integrations, third-party SDK work (forms, interactive demos, consent management). 👥 Team Support I work with a dedicated team of experienced developers, so your project always has coverage—urgent issues get handled fast, and we maintain a deep understanding of your codebase throughout, with everything delivered on time. 📈 Recent Work ✅ Untangling a WooCommerce/PayPal sandbox testing setup. ✅ Cutting a client's mobile PageSpeed score from a failing state to a passing one. ✅ Building JavaScript automation for consent and tracking scripts across a WPML multilingual site. 🤝 Let's Work Together If you need a WordPress developer who can own a project end to end—architecture, performance, payments, and ongoing maintenance—let's talk. 🔍 Keywords WordPress Developer, Full-Stack WordPress Developer, Senior WordPress Developer, WooCommerce Developer, PHP, JavaScript, TypeScript, React, HTML5, CSS3, SCSS, jQuery, MySQL, SQL, WordPress, WooCommerce, Gutenberg, Block Editor, Custom Gutenberg Blocks, Custom Themes, Plugin Development, Custom Plugins, ACF (Advanced Custom Fields), WPML, Multilingual Websites, REST API, WordPress REST API, API Integration, Third-Party APIs, Webhooks, SDK Integration, AI Development, AI Integration, AI Automation, ChatGPT, OpenAI API, Claude, GitHub Copilot, Stripe, PayPal, WooCommerce Subscriptions, WooCommerce HPOS, Performance Optimization, Google PageSpeed Insights, Core Web Vitals, Lighthouse, Caching, Asset Optimization, Database Optimization, Query Optimization, Git, GitHub, GitLab, Bitbucket, Docker, DDEV, DevKinsta, Bedrock, Composer, npm, Yarn, Vite, Webpack, WP-CLI, Linux, Apache, Nginx, CI/CD, GitHub Actions, Bug Fixing, Website Maintenance, Enterprise WordPress, Responsive Web Development, Google Tag Manager, Google Analytics, Cookie Consent, GDPR, CCPA, Tracking Scripts.

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

Experts in API Integration and Integration Architecture for complex business systems. When business systems must exchange data reliably, simple API connections are rarely enough. We design and build production-grade API integrations connecting ERP, CRM, e-commerce platforms, and internal systems - focusing on reliability, observability, and long-term maintainability. Our work centers on custom integrations that support real business operations, not fragile scripts or quick automation hacks. 🧩 What We Do 🔹 API Integration & System Connectivity Design and implementation of reliable API integrations between ERP, CRM, e-commerce, marketing, and internal systems using REST APIs, webhooks, and secure authentication. 🔹 Integration Architecture Design of robust integration architectures including data synchronization strategies, retry logic, monitoring, error handling, and long-term maintainability. 🔹 On-premise Integration Platforms Custom API integration hubs deployed on your infrastructure (Laravel / PHP), including scheduling, logging, monitoring, and full operational control. 🔹 API Development & Consulting End-to-end API development: REST API design, OAuth authentication, webhook processing, multi-system integration strategies, system audits, and integration consulting. 🔹 Data Synchronization Reliable data pipelines between ERP, CRM, analytics, and internal systems with validation, monitoring, and recovery mechanisms. ⚙️ Our Strengths ✅ Strong focus on API integration for complex business workflows (finance, e-commerce, logistics, marketing operations) ✅ Production reliability by default - logging, retries, monitoring, and alerts included ✅ Security-first architecture suitable for on-premise and private cloud deployments ✅ End-to-end ownership - from architecture and API development to deployment and long-term support 🧠 Tech Stack Languages & Frameworks: Laravel / PHP / Node.js / Python Integration Technologies: REST APIs, Webhooks, OAuth, event-driven integrations Platforms & APIs: HubSpot, QuickBooks Online, Xero, Shopify, Acumatica, BigCommerce, Airtable, Slack, Notion, Google Workspace Infrastructure: AWS, DigitalOcean, Docker, Linux 🌟 Why Clients Choose QPMSoft 💼 $400K+ earned on Upwork | 100% Job Success | 10+ years building integration systems 🤝 Clear communication, fast response times, and realistic expectations 🚀 Flexible engagement models - from focused API integrations to long-term integration platforms Whether you need API Integration, custom API Development, or reliable system integrations between ERP, CRM, and e-commerce platforms, we focus on building systems that are stable, maintainable, and production-ready.