Hire the Best Payments Freelancers
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.

👋 Hi, I'm Oleksandr. I build WordPress sites, and I rescue the ones that broke. Most of my clients are founders who'd rather run their business than learn what a CDN is — and that suits us both. Take a look below and let's see if we're a match. 🏆 Top Rated Plus (top 3% on Upwork) | $500K+ earned | 175+ jobs, 100% Job Success | 17,000+ hours tracked | 12+ years of experience You know your business inside out. Hosting, plugins and Core Web Vitals aren't where your time should go. You describe the outcome, we agree scope and budget, and I take it from there. Site from scratch, custom theme from Figma, page speed, malware cleanup, a WooCommerce store, a startup MVP — I've done it all, hundreds of times. WordPress isn't one of the things I do. It's the only thing I do. 🤝 What working with me looks like: - I make the technical calls and tell you what I chose and why, in plain English. - Jargon-free. If I slip into it, just say so and I'll explain it another way. - AI is part of my toolkit and stays on my side of the work. If you'd rather not think about it, you won't have to. - I try to flag things early — better to raise a risk now than after launch. - If I see a better route than the one you have in mind, I'll say so. You're hiring me for judgement, not just execution. - Scope and pricing agreed upfront. - Based in Ukraine (GMT+3): my day fully covers European business hours and overlaps US hours by 6 hours daily. Typical reply in 1–60 minutes. ✅ WordPress Development & Design: - Full WordPress website development, from concept to launch - Custom themes from Figma, PSD, Adobe XD, Sketch — pixel-perfect - Elementor / BricksBuilder / Gutenberg / Divi / WPBakery / Visual Composer - ACF (Advanced Custom Fields) — dynamic layouts, content blocks - Custom post types, taxonomies, filters, post meta - Custom Gutenberg blocks & block themes (FSE) - Plugin customization, conflict fixes, custom plugin development - Redesign & modernization of old WordPress sites - Client-friendly admin dashboards - White-label WordPress development for agencies - Vibecode cleanup — turning AI-generated code into production-ready sites 🛒 WooCommerce: - Store setup & configuration from scratch - Checkout customization & conversion optimization - Subscriptions, bookings, memberships, digital products - Payment gateways - Product imports, variations, bulk pricing, B2B/wholesale flows - Shipping, tax and invoicing setup - Store migration to WooCommerce from other platforms ⚡ Performance & Security: - Speed optimization (WP Rocket, Autoptimize, LiteSpeed, Core Web Vitals) - PageSpeed & GTmetrix audits with before/after reports - Database optimization & cleanup - Security hardening, malware removal, Wordfence setup - Hacked site recovery, backups, disaster prevention - Hosting optimization: SiteGround, Hostinger, Bluehost, AWS, DigitalOcean, WPEngine - Zero-downtime migrations between hosts and domains 🔍 SEO, Analytics & Integrations: - Yoast SEO / Rank Math setup, blog & SEO structure - Schema structured data & rich snippets - Google Analytics (GA4), Search Console, Tag Manager - Multi-language sites (WPML, Polylang) - Forms: Gravity Forms, Contact Form 7, Ninja Forms - Email integrations: Mailchimp, MailerLite, Brevo - Accessibility fixes (WCAG 2.1 AA) - GDPR / CCPA cookie consent & Google Consent Mode v2 🚀 MVP Development for Startups Lean, scalable MVPs on a WordPress backend: - Gated content, custom dashboards, booking engines - Multi-user flows: vendors ↔ clients ↔ admin - Make, Zapier, Boost.space, Airtable integrations - Business logic automation & external API connections - Intuitive, no-code-friendly admin areas - From Figma to MVP in weeks, not months 🧠 Why Clients Hire Me: - 175+ Upwork jobs at 100% Job Success, 300+ projects overall in 12+ years - 17,000+ hours tracked — over 8 years of full-time work logged on Upwork alone - Long-term support after launch 🔍 Clients Often Search For: WordPress expert, WP developer, WordPress designer, fix WordPress site, Figma to WordPress, Elementor pro, BricksBuilder expert, Divi expert, WordPress bug fix, WordPress malware cleanup, WordPress site hacked fix, WooCommerce developer, WooCommerce setup, WooCommerce checkout customization, WordPress SEO, ACF developer, WP speed optimization, Core Web Vitals fix, mobile responsive fix, WP Rocket expert, custom WordPress theme, Gutenberg blocks, WordPress MVP developer, startup MVP on WordPress, WordPress backend for SaaS, no-code MVP builder, multilingual WordPress site, WPML expert, WP migration expert, WordPress hosting migration, WP plugin customization, custom WordPress plugin, redesign WordPress website, WordPress performance audit, WordPress security audit, WordPress maintenance, WordPress dashboard for clients, WordPress landing page, WordPress blog setup, WordPress LMS, WordPress booking system, web developer, seo audit, PM, BM Send me a message or invite me to your job 🚀 Updated August 13

⭐️ Highly skilled QA Engineer with over 9 years of experience in various types of testing, including web, mobile, and desktop platforms. Proficient in creating test documentation, working with Agile methodologies, and utilizing a wide range of testing tools and frameworks. ⭐️Top Rated Plus freelancer⭐️ 100% Job Success 📌Summary of Skills: * Manual Testing Mobile Applications (Android & IOS with Testflight installed) * Manual Testing of Desktop Software and Web-based Software * Excellent bug finder with a good eye for details, receiving awards and bonuses * Document creation (Test plan, test case, test script, test scenario, user's manual) * Report Bugging Documentation * Project Handover Documentation * Worked on Agile Methodologies 📌Scope of Testing: * Manual Testing (Functional testing such as smoke and sanity testing, regression, usability, alpha-beta, positive and negative, GUI, exploratory, API, and end-to-end testing) * Mobile Apps Testing * Game app testing(mobile/desktop) * Cross-browser Testing * UI/UX Testing/Feature suggestion * Test media platforms such as Roku, Visio, Tizen, Apple TV, Fire TV, and Android TV - 5 years of experience 📌Technical Experience: * Platforms: Windows XP, Windows 7, Windows 10 * Database: MySQL * Remote Applications: TeamViewer, Remote Desktop Application * Defect Tracking and Management Tools: JIRA, Trello, X-Ray, Excel, Youtrack, Zephir, Mantis * Other software/tools: Browserstack, Google Apps, Dropbox, Postman, Slack, Microsoft Teams * Microsoft Applications and documentation tools 📌Devices: * Android - Xiaomi mi 9t PRO * iPhone XR, iPhone 12 plus, iPhone 13 (TestFlight ready) * Tablet - iPad 8 gen * Apple TV * Google Chromecast ⭐️ Why you should choose me over another freelancer ⭐️ - I provide high-quality and professional work so that the customer has a positive experience of working with me, is satisfied with the result, and wants to come back to me next time with a new job offer. - I believe that my passion for testing and ability to learn, adapt to new challenges, and grow make me a strong competitor. Have any questions or want to discuss your projects? Please do not hesitate to contact me. Let’s get started! Cheers! ------------------------------------------------------------------------------------------------ Keywords: Quality Control, Manual Testing, Quality Assurance, QA Testing, Web Testing, Bug Reports, GUI Testing, UI Testing, Software QA, QA Engineering, Desktop Application Testing, Functional Testing, Non-functional, Software Testing, Web App Tester, Usability Testing, User Acceptance Testing, Defect Tracking, Test Reporting, Test Plan, Test Case, Data Testing, Website Testing, User Story, Beta Tester, Stability/Reliability testing, Compatibility testing, Black box Testing, Cross-Browser Testing, Cross-Device Compatibility, Retesting, Front End Testing, Accessibility testing, Web Content Accessibility Guidelines (WCAG).

Brands owned by Rollins, the S&P 500 company (~$3.4B revenue; NYSE: ROL) are currently using AI sales agents I built. One sold 769 accounts and generated $620K for a single customer in a year (public case study on sellifyai's website); another made $1M in a month. From CEO Thomas K. Lundberg ($350M exit): "Vlad has been incredible to work with" If you shoot me an invitation or message i'll send you a personalised video back on how i may be able to help you! A little more about me: 👋 Hi! I'm Vlad - Senior AI Engineer · Top Rated Plus (top 3%) · Claude Certified Architect, Anthropic. Agentic AI and production LLM applications. 🔧 THREE THINGS I DO 1️⃣ Agentic AI in production. Multi-agent systems, agentic workflows and agent orchestration (LangGraph, Claude Agent SDK, CrewAI, LlamaIndex) with tool calling and structured outputs, wired into your CRM and internal tools: HubSpot, Monday com, SharePoint, Microsoft 365, and the legacy CRMs. I help you pick what stays deterministic code and what needs an agent. Sensitive steps wait for human approval, every action lands in an audit trail, and an evaluation framework runs on every change so quality holds at scale. I also take over half-built agent projects that broke with real users and carry them from prototype to production. 2️⃣ Claude ecosystem engineering. Claude API, Claude Code, Claude Agent SDK, Anthropic API, Claude Cowork, Claude Skills. MCP server design (Model Context Protocol), prompt caching, model routing, token cost optimization. I have cut Anthropic API bills, with before/after evals proving quality held. I also set teams up with AI coding agents: Claude Code and Cursor in the daily loop, code review and pull requests still owned by people. 3️⃣ Private LLMs, self-hosted. Open-weight models (Qwen, Llama, Mistral) with vLLM model serving on your own GPU, Ollama for local runs, LiteLLM gateways, fine-tuning when a prompt will not get there. Builds stay provider-neutral, so a hosted model can move on-premises later without rebuilding retrieval. GDPR and data residency come up constantly with EU clients. ✅ HOW I WORK Production AI systems break around month six, once the prompt has been edited twenty times and nobody recalls what still works. I prevent this with: • Evaluation frameworks, automated testing and regression tests on every change; model evaluation protects against regressions. • Guardrails, prompt injection defense and human-in-the-loop review. Answers stay grounded in your own sources, so hallucinations get caught. • Reliable AI plumbing: retries, idempotency, queues, audit logging, observability, monitoring. Least-privilege access and secrets management, so agents never touch raw credentials. RBAC and multi-tenant setups. • Cloud deployment your team can maintain (Docker, AWS, GitHub Actions CI/CD), with docs and training. 📈 RESULTS (public case studies) Two years on the founding team at Sellify AI, outcome-priced AI sales agents for US pest control, paid only when the AI sells: • Over $1M in new revenue in one month for HomeTeam, one of the largest US pest control firms • $620K in new sales and 1,100 new accounts for Ninefold • I built the legacy CRM integrations (FieldRoutes, PestPac) rivals still have not copied. They closed the six-figure clients Since then, contract Senior AI Engineer at a recruitment SaaS, working directly with the founder: a job-monitoring agent live at several agencies with a human approval step, plus an evaluation framework their developers run without me. Also a legal RAG agent over an 89,600-section Norwegian law corpus, quote-verified against the law. ⭐⭐⭐⭐⭐ "Very sharp and understands the intricacies and needs of our company. Have trusted him with important tasks, and he's always delivered." - Thomas K. Lundberg, CEO Sellify AI ($350M prior exit) 🚀 HOW TO START 🔍 Free teardown, 48 hours. Send 10 traces where your AI got it wrong. You get the three root causes and what I would fix first, in writing. 📋 AI Assessment & Roadmap, from $2,500, ~2 weeks. Architecture, what it costs at your size, what breaks first, a plan in priority order. 🛠️ Then we build. I work independently. Milestone or hourly, EU/US hours. 🛠️ STACK AI/LLM: Anthropic Claude, Claude Code, Claude Agent SDK, OpenAI, Azure OpenAI (EU/GDPR), AWS Bedrock, Gemini · multi-agent and LLM orchestration (LangGraph, LangChain, CrewAI, LlamaIndex) · MCP server design · RAG and AI knowledge bases (pgvector, Qdrant, hybrid search, reranking, embeddings) · LLMOps: evals, observability, prompt caching, model routing, cost optimization · generative AI (GenAI), guardrails, structured outputs, tool use / function calling · fine-tuning, vLLM, self-hosted open-weight models (Qwen, Llama, Mistral) · document extraction, OCR Engineering: Python, TypeScript/Node.js, PostgreSQL, Redis, Celery, Docker, AWS, GitHub Actions CI/CD, REST/webhooks/OAuth · Shopify, Slack, Notion, WhatsApp Business API Domains: vertical SaaS · recruitment

🏆 Top Rated Plus (Top 1% Upwork talent) ☕ Started working as web developer in 1999 🔥 Expertise in front-end, back-end, and server administration 🔐Always keeping in mind security and productivity aspects 🎓Master and bachelor degrees in computer science Let's make your project successful! 🚀🚀🚀

WordPress + WooCommerce Developer | Elementor, Divi | PHP, HTML, CSS | Technical Consulting Full-time Upwork freelancer focused on resolving web-related bottlenecks for marketing agencies and small to medium sized businesses. I collaborate with agency teams and business owners to build, refine and support WordPress sites that are minimal, fast and responsive. Core services: WordPress: - Website design and builds from start to finish - Layouts using Elementor, Divi, Visual Composer and similar builders - PHP development and debugging - Custom plugins, plugin modification - Theme customization with HTML, CSS and JS - Performance and site optimization - Multi-step forms with conditional logic - Site transfers and migrations WooCommerce: - Product, cart and checkout customization - WooCommerce plugin customization and modifications - Custom invoicing and workflow solutions Hosting, domains and email: - Domain setup and transfers - DNS troubleshooting, TCP/IP, VPNs - SMTP and email deliverability issues - Email spam correction and mitigation How I work: - Consulting, troubleshooting and implementation with clear technical communication - Strong in revamps where I have creative control or a clear style guide to follow - Clean UI, practical UX, performance-first decisions Background: Before consulting, I worked in corporate IT from desktop support through service desk management across distributed teams in the United States. Network administration experience translates well to diagnosing DNS, domain and email issues and working with Google Cloud solutions. References and recommendations available on request.