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Full lifecycle: requirements analysis and architecture design through implementation, maintenance, and growth of SaaS products - so founders can focus on the business, not the build. For the past years I ran a crowdsourced logo design platform: 75,000 B2B clients, 14M logos, 99.9% uptime against a 99.75% SLA. At peak I led a team of 7 while remaining the primary engineer on core systems. Experienced with large production codebases without regressions - test coverage, migrations, and zero-downtime deployment. I onboard quickly into unfamiliar teams and projects. SKILLS System Design, Database Design, JavaScript, PHP, MySQL, Node, React, TypeScript, Redis, ElasticSearch, Docker, Ansible, PayPal integration, Nginx, PostgreSQL, Apache Kafka, Sphinx, Cloudflare, S3, SVG, LESS, jQuery, XSLT, Mocha, Selenium, Vite, TailwindCSS, A/B testing, PDF rendering. WORK HISTORY 2008 - 2026 Quinn Ventures Inc. Technical Lead and Software Engineer, working directly with the founder - a continuous Upwork engagement. Owned core architecture for all SaaS products and day-to-day engineering across multiple technology generations. Built and led a team of up to 7 (developers, system administrators, designers), scaling it up and down by project phase - hiring and onboarding, work breakdown, code review, and release planning while staying hands-on in the codebase. LogoTournament - a crowdsourced logo design platform: 75,000 B2B clients, 14M logos. Highlights: - Sustained 99.9% uptime against a 99.75% SLA across 18 years of continuous development - Migrated the platform through three infrastructure generations with zero downtime: storage (local → Rackspace → S3), search (Sphinx → ElasticSearch), plus two full front-end rebuilds - Payments: credit card and PayPal, multi-tier pricing, fraud protection - chargeback rate below 1% - Performance: Redis session and page caching; Kafka for delayed processing, notifications, analytics; Rate Limiting - Admin back-end with performance, statistics, and feedback tracking; sales history, tax, and payment-hold reporting - UI: Production A/B testing for new features, vector drawing and annotation tools, React-based admin back-end. - OpenAI integration for portfolio classification and contest brief analysis - Infrastructure: Ansible IaC, Cloudflare WAF, monitoring/alerting/backups, Mocha/Selenium functional tests Skills: MySQL, PHP, Redis, Apache Kafka, SVG, LESS, React, JavaScript, Docker, ElasticSearch, A/B testing, Sphinx, Node, Mocha, Selenium, Ansible, Ubuntu, Linux, OpenAI, S3 NameSampler - AI-powered SaaS for Quinn Ventures, a modern stack and LLM orchestration: React + TypeScript (Vite, Tailwind CSS), Node, OpenAI integration, deployed on Ubuntu. GUI orchestration of LLM prompts across 83 structured naming methodologies. Features: sorting, favorites, and on-the-fly domain availability checks. Internal product venture, sunset by the client. Skills: Nginx, React, TypeScript, Vite, Tailwind CSS, Node, OpenAI. PathJet - Productivity SPA for Quinn Ventures: Kanban board with integrated Pomodoro timer and productivity analytics. Built end-to-end - React front-end, PHP back-end. Internal product venture, sunset by the client. Skills: React, JavaScript, PHP, Node, Babel, ES6, PostgreSQL Plus numerous other products over the years. The engagement concluded in June 2026, when AI image generation made the LogoTournament business model obsolete. Reference available from Tyler Quinn, CEO, Quinn Ventures Inc. (Canada). EARLIER EXPERIENCE (2003 - 2013) 99znakov (discontinued) Daily Commute Carpooling & Dating Platform. A two-sided marketplace matching drivers and passengers on overlapping daily routes via geo and time analysis. Features: SMS API integration, in-app chat, social user profiles, content moderation, and a community forum. Role: Founder, lead developer, and project manager; team of 3. Skills: PostgreSQL, PHP, Zend, JavaScript, jQuery, Sockets, Android WebView app Online stock trading system - Core architecture, database schema, and optimization for a multi-server trading platform: bank offer submission, AJAX market indexes, inline editing, dynamic XSLT, subscriptions, and a custom Win32 trading browser with technical analysis (EMA, SMA, RSI). Arabic language support. Long-term Upwork engagement. Skills: Sockets, AJAX, XSLT, PostgreSQL, PHP. Role: Lead developer and project manager, team of 4. Sports league management system - League, facility, player, and team management with manual and automatic game scheduling, contract and time-slot operations, and CSV reporting. Role: PHP middle developer in a team. Automated car park software - Operator console, billing with multiple tariff plans, photo/video capture, magnetic card reader and controller programming. Role: UI, database design, and billing; startup team of 3. PERSONAL SIDE PROJECT Reverse-engineered and modified the China-market infotainment system of a 2020-2023 Chevrolet Equinox ADDITIONAL PADI licensed diver.

Dear Hiring Manager, welcome to my profile. 🏆 Top Rated Senior Full-Stack WordPress & WooCommerce Expert With 10+ years of experience and 1000+ projects completed, I focus on results — not just code. I help businesses fix, optimize, and scale WordPress websites — fast and reliably. Main expertise: ✔ Fix critical bugs and errors (24–48h) ✔ WooCommerce checkout & payment issues (prevent lost sales) ✔ Figma to WordPress (pixel-perfect, fast, responsive) ✔ Custom development (ACF Pro, custom themes, custom plugins) ✔ Builders Expert (Elementor/WP Backery/Divi...) ✔ Plugin setup, customization themes, and conflict resolution ✔ Speed optimization (Google PageSpeed 85–95+) ✔ REST API and AI integrations (OpenAI / ChatGPT) I am very fond of responsive web development, as I am fond of projects online stores if you need someone who will bring to the end of this work, please contact me. For me is important to perform quality work for the client, and not less important to satisfy the customer order and made him satisfied. When I’m working on a project, I don’t want just to meet deadlines. Rather, I prefer to complete the project well ahead of schedule. Why choose me: ✔ Save your time with fast and accurate solutions ✔ Long-term support after ending contract ✔ Fast responses and reliable communication ✔ Never abandoned a project or complex task Selected projects: ✔ Long-term WordPress development – $11,000+ ✔ Custom WooCommerce solutions – $3,000+ ✔ Ongoing support & improvements – $1,500+ Many of my clients come back because I solve problems quickly and keep their websites running smoothly. ⚙ Deeper ⚙️ ⚙️ Backend Stack: Have extensive experience with: - PHP 7.x/8.x | OOP | MVC | SOLID | Design Patterns - REST API | GraphQL | SOAP | XML | JSON | cURL | Webhooks - Apache | Nginx | Linux | cPanel | Plesk - MySQL | MariaDB | PostgreSQL | MongoDB | NoSQL | SQLite - Redis | Memcached | RabbitMQ | Queue Systems - Composer | WP-CLI | Cron Jobs - Git | GitHub | GitLab | Bitbucket | SVN - Docker | CI/CD | Agile - JWT | OAuth | OAuth2 | API Integrations 💻 Frontend Stack: - HTML5 | CSS3 | SCSS | SASS | JavaScript (ES6+) | TypeScript - jQuery | AJAX | JSON | Fetch API | Axios - Vue.js | Vuex | Nuxt.js | Vuetify | Quasar | Vuely - Angular | React - Bootstrap | Tailwind CSS | BEM - Pixel Perfect | Responsive Design | Mobile First - Cross-Browser Compatibility | Retina Ready - WCAG 2.1 Accessibility Standards | W3C Standards - Figma | Adobe XD | PSD | AI | Sketch to HTML/WordPress - CSS Animations | GSAP | Canvas 🌐 WordPress Stack: Custom Theme Development | Custom Plugin Development | WordPress REST API | Gutenberg Block Development | WordPress Multisite | WP-CLI | Custom Post Types (CPT) | Custom Taxonomies | ACF Pro | Meta Box | Shortcodes | Widgets | Hooks (Actions & Filters) | Child Themes | Theme Customizer | Template Overrides | Multilingual Websites | Headless WordPress 🎨 Themes: Astra | GeneratePress | Kadence | Divi | Avada | Flatsome (UX Builder) | WoodMart | Porto | OceanWP | Betheme | Enfold | Bridge | Salient | Newspaper | The7 | X Theme | Jupiter | Impreza | Uncode | Custom Themes 🧱 Page Builders: Elementor Pro | Beaver Builder | Divi Builder | WPBakery | Gutenberg | Bricks Builder | Thrive Architect | Visual Composer | UX Builder (Flatsome) 📝 Forms: Gravity Forms | WPForms | CF7 | Ninja Forms | Fluent Forms | Formidable Forms | Everest Forms | Caldera Forms | Quform 🛒 WooCommerce: Custom Checkout | Custom Payment Gateways | Shipping Methods | Subscriptions | Bookings | Memberships | Product Add-ons | Dynamic Pricing | Composite Products | Variable Products | Store API | HPOS Compatibility 🔍 SEO: Yoast SEO | Rank Math | All in One SEO | Schema Markup | Rich Snippets | XML Sitemap | Open Graph | Core Web Vitals ⚡ Performance: WP Rocket | LiteSpeed Cache | W3 Total Cache | Perfmatters | Asset Cleanup | Redis Cache | CDN Integration | Cloudflare | Image Optimization | Lazy Loading 🛡️ Security: Wordfence | Sucuri | iThemes Security | Malware Removal | Hardening | SSL | reCAPTCHA 📧 Email & Marketing: Mailchimp | Brevo (Sendinblue) | Klaviyo | ActiveCampaign | MailPoet | Constant Contact | Campaign Monitor | ConvertKit | MailerLite | HubSpot | Mailgun | SendGrid | Amazon SES | SMTP Configuration 🔌 Integrations & APIs: Stripe | PayPal | Authorize.Net | Square | Braintree | Mollie | Google Sheets | Google Maps API | Google Analytics | Google Tag Manager | Google Merchant Center | Facebook Pixel | Meta Conversions API | Zapier | Calendly | Twilio 🔄 Migration & Maintenance: Website Migration | Database Migration | Backup & Restore | Staging Environments | Version Upgrades | Plugin Conflict Resolution | Bug Fixing | Security Audits | Malware Cleanup 🤖 Data & Automation: CSV/XML Import & Export | Web Scraping | Data Parsers | Custom Parsers | Feed Generation | API Sync 🏗️ CMS & Frameworks: WordPress | Laravel | Symfony | Drupal | Bitrix | Yii | OpenCart | Shopify | Smarty

Full-stack developer with a proven Upwork track record (100% Job Success, $200K+ earned, 7,400+ hours) building production Angular, Ionic and ASP.NET Core applications. Alongside my Upwork work, I'm currently building AI-driven features professionally: an ASP.NET Core + Entity Framework + Angular/Tailwind e-commerce platform that syncs its product catalog from a 1C database, plus a RAG system and an AI shopping-consultant chatbot that helps customers pick the right product. I use Claude Code daily to speed up and automate development work, and I run local LLMs via Ollama for cost-efficient, privacy-friendly RAG pipelines. Core Expertise ✔ Frontend: Angular (2 to 21), TypeScript, RxJS, Signals, Ionic, TailwindCSS, Angular Material ✔ Backend: ASP.NET Core, .NET, C#, Entity Framework, Node.js ✔ AI & Automation: Claude Code-assisted development, RAG pipelines (PgVector, embeddings), local LLM deployment via Ollama, OpenAI/Anthropic API integration, n8n workflow automation ✔ Databases: PostgreSQL (with PgVector), MS SQL Server, MySQL, Redis ✔ Integrations: RESTful APIs, ERP/1C data sync, e-commerce catalogs, OAuth, third-party APIs What I Deliver ✔ Production-grade Angular/Ionic SPAs and admin panels backed by ASP.NET Core ✔ E-commerce sites with catalog sync from ERP/1C systems ✔ RAG-powered AI consultants/chatbots that help customers navigate a product catalog ✔ Local LLM deployments (Ollama) for clients who want to avoid recurring API costs or need extra data privacy ✔ Clean handoff, regular communication, and code you can maintain long after the project ends Why Work With Me 35+ completed Upwork contracts and a 100% Job Success score speak for reliability and communication. On top of that, I'm actively hands-on with the current generation of AI tooling: Claude Code in my daily workflow, and RAG/local-LLM systems in a live production project. I bring both a solid full-stack foundation and up-to-date AI skills to every project. Let's talk about your Angular app, your .NET backend, or the AI assistant you want to add to your product.

As a seasoned professional with 20 years of experience in back-end development and 7 years in machine learning, I have a proven track record of building high-quality, scalable web applications, APIs, and AI solutions. I am proficient in both front-end and back-end development, leveraging a wide array of technologies to deliver seamless user experiences, robust server-side solutions, and advanced machine learning models. WEB DEVELOPMENT Back-End: Building robust server-side logic with Django, FastAPI, and Flask. Full Stack: Seamlessly integrating front-end and back-end technologies for comprehensive solutions. API DEVELOPMENT RESTful APIs: Designing and implementing APIs with Django REST Framework. Microservices: Developing scalable microservices using Flask and FastAPI. Data Management: Utilizing SQLAlchemy and Alembic for efficient database interactions. Data Validation: Ensuring data integrity with Pydantic. DATABASE DEVELOPMENT Relational Databases: Designing and managing schemas in PostgreSQL. Analytical Databases: Implementing high-performance data storage solutions with Clickhouse. GUI DEVELOPMENT Desktop Applications: Creating user-friendly desktop applications using Qt/PyQt. AUTOMATION AND BOTS Telegram Bots: Developing bots for various purposes on the Telegram platform. Console Utilities: Automating text manipulation, email handling, image processing, and other routine tasks. MACHINE LEARNING & DEEP LEARNING Model Development: Design, train, and optimize machine learning and deep learning models. Frameworks: Proficient with TensorFlow, PyTorch, Keras, Scikit-learn. Hyperparameter Tuning: Expert in techniques to improve model performance. COMPUTER VISION Image Processing: Object detection, image classification, segmentation. Libraries: OpenCV, YOLO, SSD, Mask R-CNN. NATURAL LANGUAGE PROCESSING (NLP) Text Analysis: Sentiment analysis, text summarization, named entity recognition. Tools: NLTK, SpaCy, BERT, GPT, Transformers. RECOMMENDER SYSTEMS Personalization: Collaborative filtering, content-based filtering, hybrid methods. Implementation: Building recommendation engines to enhance user experience. DATA ENGINEERING Workflow Orchestration: Apache Airflow, dbt. Data Management: Clickhouse, Metabase, Apache Nifi. ETL Processes: Extract, transform, load workflows for data warehousing. Data Preparation and Exploratory Data Analysis (EDA) Data Cleaning: Handling missing values, outlier detection. Visualization: Creating insightful visualizations using Matplotlib, Seaborn, Plotly. Statistical Analysis: Descriptive statistics, hypothesis testing. MODEL DEPLOYMENT Deployment Platforms: AWS SageMaker, Google AI Platform, Azure ML. Frameworks: Flask, FastAPI, Starlite. Containerization: Docker, Kubernetes for scalable deployment solutions. ADDITIONAL SKILLS Programming Languages: Python, TypeScript, SQL, C++, Rust, JavaScript. Web Frameworks: Django, Flask, FastAPI, React. ORM: SQLAlchemy. Migrations: Alembic. Data Validation: Pydantic. Version Control: Git, GitHub, GitLab. DevOps: Docker for containerization and orchestration. PROFESSIONAL ATTRIBUTES Strong problem-solving skills with an analytical mindset and a passion for clean, efficient code. Excellent communication, teamwork, and collaboration abilities. Commitment to continuous learning and staying updated with the latest advancements in both web development and AI/ML technologies.

Hi there, My name's Sergei, I'm a senior Software Architect and Project Manager with over 19 years of experience in the software development industry. I'm backed by a team of seasoned software engineers, designers, and QA engineers whom I gathered and trained myself. I personally work in the following roles: - Technical Advisor - Software Architect - Product Owner / Project Manager - Technical Lead (implementation of critical parts of code) My team - Storytelling Software - offers the following services: - Existing system audit (architecture, software design, integrations) - API integrations between third-party systems - Complex Project end-to-end development (MVP and beyond) - AI-empowered, CRMs, SaaS, unique project ideas. - UX/UI design (wireframes, clickable prototypes, complete design systems, user-facing design) - Web Apps (React/TypeScript/Python/FastAPI) - Mobile Apps (Flutter/Dart/Native) Our clients: - Save up to 53% compared to building and maintaining an in-house IT department - Like interacting with mature professionals who take time to understand their business and needs - Free up their schedule because we "are able to work with minimal supervision", according to Will Zoltan Bell, Founder and Director at Nearcut Just drop me a line to start the conversation and get TRULY realistic estimation of your project for FREE.

🚀 I build AI-powered web apps with React, Next.js, TypeScript, and modern LLM APIs. I have 6 years of front-end experience, including work on products for banks and large corporations, where code quality, security, and performance actually matter. Today I mainly help founders and teams add AI features to real products, not just build demos. ✅ I can help you with: - AI chatbots for websites, SaaS products, and internal tools - OpenAI and Claude API integrations - ChatGPT-like interfaces with streaming responses - AI assistants with structured JSON outputs - RAG pipelines: chat with your documents and data - AI agent frameworks: OpenClaw and Hermes Agent setup, configuration, and troubleshooting - Telegram bots and conversational products - React/Next.js dashboards, admin panels, complex forms, and SPAs - Vercel deployment, frontend bug fixing, and performance improvements 🤖 Recent work includes an AI English tutor bot: Claude API, deterministic state management, Telegram integration, and a lesson-planning system. 🛠 My usual stack: React, Next.js, TypeScript, Tailwind CSS, Node.js, FastAPI, Supabase, OpenAI API, Anthropic Claude API, Vercel. 💼 What you can expect: - clear scope before development starts - clean, typed code - fast replies - practical technical decisions - no overbuilt architecture unless your product actually needs it 📩 If you need to add an AI chatbot, assistant, agent interface, or AI feature to your product, send me a short description. I'll reply with a clear plan, timeline, and estimate.