Full Stack Developer | 5M software End-Users Impacted | $200K+ Total Earnings | Expert-Vetted (Top 1% Upwork) | 26 Projects | 100% Job Success | 12+ Years on Upwork | 5339+ Hours Worked | TOP RATED PLUS – Top 3% of companies | 15+ Countries Covered 🙈 “Can we just quickly fix this?” 🙊 “It’s probably just a small change.” 🙉 “Let’s ship first and think later.” I am a CEO and Business Manager at Peppernode. I help create systems where architecture matters, decisions matter, and the cost of mistakes is higher than the cost of doing it right. Call me Illia. ✅ Full Stack Developer React ✅ React Developer ✅ React Native Developer ✅ React Native Mobile Developer ✅ Python Developer ✅ Front end Developer ✅ Mobile App Developer ✅ SaaS Developer With 12+ years of experience, I specialize in building scalable SaaS platforms, high-performance mobile applications, and production systems designed for long-term growth. I work as a React Full Stack Developer, React Native App Developer, React Developer, and Python Developer helping startups and established businesses transform ideas into reliable products that scale. I combine web development, Mobile App Developer, and business analysis to connect business goals with technical execution. My react native full stack background helps align product strategy, architecture, and delivery. 🏆 Why Clients Choose Me As a Full Stack Developer React with 31 successful projects delivered across 15+ countries, I've helped build products now serving more than 5 million end-users worldwide. With 100% Job Success, $200K+ earned, and 5,339+ hours worked on Upwork, I bring proven experience designing scalable applications, validating product strategies, and helping businesses make the right technical decisions from day one. 🚀 SaaS Product Development I build modern SaaS platforms as a Full Stack Developer React using React, Python, Firebase, scalable architecture built to scale. I work as a React Developer Firebase specialist delivering connected experiences across frontend and backend systems. My experience includes architecture planning, MVP development, frontend/backend implementation, payment integrations, and product evolution. 📱 React Native App Development As a React Native Developer and React Native App Developer, I build cross-platform applications delivering consistent experiences across iOS and Android. As a React Developer and Mobile App Developer, I deliver React Native Mobile solutions built for reliability and performance. As a react native developer expo specialist, I move products from MVP to production while maintaining a high-quality user experience. My experience includes mobile app development react native projects for startups and businesses requiring speed, flexibility, and long-term scalability. My work includes React Native and Expo development, feature delivery as a full stack developer react native, mobile MVPs and enterprise applications, API integrations, App Store and Google Play releases, performance optimization, product support. I have experience as a node js react native mobile developer building connected mobile ecosystems powered by scalable backend services. 🍽 Restaurant Ordering Systems I have experience developing restaurant ordering solutions serving thousands of daily users, with a strong focus on reliability, operational efficiency, and seamless customer experiences. Several included React Native Mobile experiences for customers and operational teams. These systems require solid architecture and stable integrations. 📌 Existing Product Modernization Many teams come to me after moving too fast. As a Front End Developer React and Full Stack Developer React, I improve existing applications through refactoring unstable codebases, optimizing performance bottlenecks, introducing scalable architecture, reducing technical debt, and expanding functionality without sacrificing maintainability. 🤖 AI Integrations & Automation I work as a Full Stack Developer AI building solutions with OpenAI API, Gemini, LangChain, Copilot, and modern AI workflows to create intelligent product experiences, including AI-powered features, chat interfaces, workflow automation, knowledge retrieval, and productivity enhancements. 🔧 Workflow & Tech Stack Discovery and planning begin with business analysis, technical discovery, architecture decisions, and product strategy. Frontend technologies include React, React Native, Expo, TypeScript, JS, HTML5, CSS. Backend development is built with Python, FastAPI, Django, Node.js, REST APIs, GraphQL, PostgreSQL, MySQL, Firebase, Stripe integrations. As a Python Full Stack Developer Flask specialist, I focus on maintainable systems, integrations, and architectures designed for long-term evolution. 🚀 Need a Web Developer, React Developer, React Native Developer, Full Stack Developer React Node or Python Full Stack Developer who thinks beyond code and builds products designed to scale? Let’s talk.

I have more than 18 years of work experience in the Information Technology field covering software development, system analysis and software quality control and I have worked during this period on many projects in the middle east, UK, USA and Australia. In addition to that I got MSc in Web Technology. Main skills are; SharePoint Online, ASP.NET MVC, .NET core, Power Apps, MS Flow, Copilot Agents and more.

My background sits at the intersection of full-stack engineering and business strategy, with a focus on WordPress and PHP platforms, C++ systems, CRM and AI automation, and CMS-driven products that deliver lasting value. At Pearl Health, I worked as a technical lead engineer with a business advisory role, primarily on legacy and enterprise healthcare systems. I led modernization efforts across WordPress and HubSpot CMS platforms, PHP-based development, API integrations, and performance improvements, while also supporting value-based care partnerships by helping teams align technical capabilities with ACO REACH programs, PCP independence, and post-acute care network integration. I do a lot of custom WordPress work, including theme and plugin development, performance tuning, integrations, modern JavaScript, cloud deployment, and CRM and AI automation through workflows and APIs, with experience integrating platforms such as Salesforce, NetSuite, and Airtable. I also work with databases and backend systems, and use C# or Java when projects call for it. With a blend of technical experience, creative direction, and strategic insight, I focus on building software and systems that solve real problems and hold up over time. I enjoy working with people who care about creating lasting value through thoughtful, well-built solutions.

Logo Design is my passion while animation, explainer videos, and video editing is something I love to do. If you have a new brand or an already established one but want to do branding design, I will be your one point solution. In design, I will help in logo design, website design as well as brand guidelines that includes color palette, font typography, brand identity, logo usage guide, business card, letterhead, stamp design, logo mockups, logo animation, 2D logo reveal, video intro & outro, brand identity & guidelines, brand positioning, brand book design, social media design, print design, corporate brand identity, graphic design & vector graphic. I will be your best logo designer on Upwork with expertise in Adobe Illustrator, Adobe Photoshop, and Figma. In animation, my expertise is explainer videos and video editing as I work in Adobe After Effects and Adobe Premiere Pro. If you need a character video, vector graphics, cartoon animaton, motion graphics, screencast video, Saas Explainer Video, whiteboard, website explainer, app explainer, typography animation, hero section video, website video, stock video, custom brand video, video commercial, video production, video post-editing, 2D animation, audio editing, storyboarding, illustrations, lottie, and videography. Each step is custom, shared with you for approval at various stages, unlimited feedback, and I deliver complete final files once the project is approved. Please send me a DM message via Upwork and we can discuss about your brand. Project consultation is free of cost.

Do you need IT help for your business but find working with developers difficult? Are you struggling to achieve your business goals with the software you use? I'm here to take this burden off your shoulders so that you can focus on what you do best - your business. Programming, for me, is a tool only - not an objective itself. I will take care of all IT work and make sure it is aligned with your goals. Here are the ways I help companies thrive: • Building XML related systems — many times XML is the best choice for exchanging data, especially when you need to control the structure of nested nodes of data. I'll help you utilize the best of XML technology so it can effectively serve your business needs. • Design of tailored systems — when your business model that needs a boost with an automated, intelligent software. I'll work with you closely to understand the goals and build software that moves your productivity and profits to a completely new level. • Optimization of existing systems — when your software doesn't fully serve your needs. I'll transform it in the most effective way to keep all that is good in it and add the new value you are seeking. • Building a team - when you need to effectively achieve your IT goals. I'll find the best people that can achieve your goals within the budget and time. • Building a website - when you want to improve your online presence. I'll design a beautiful and fast website that brings you more clients and conversions. You will see a major increase in your productivity and profitability, your systems will start bringing you clients and money. With me, you get someone who understands your business and speaks your language - an honest professional whom you can trust. What clients say about my work: "Single handedly the best developer I have ever come across in my 15 years working in this industry. I cannot recommend Jacek enough. His professionalism, quality of work, delivery, communication are all of the highest quality. I will be putting more work Jacek's way." - Richard "I've already scheduled another project with Jacek. It's always a pleasure!" - Cheryl "Designed the page within my guidelines and requirements. Made front end elegant and functional. Back end was clean and user-friendly. Fantastic communication, extensive expertise. Will hire in future" - Vitold Technologies I work with: * XSLT, XPath, XML, XML Schema, exist-db, Apache FOP, Ibex, Xalan, MSXSL, Saxon, Dita, Docbook, EXSLT, XQuery, xsltproc, HTML5, XHTML, SVG, SpreadsheetML, WordProcessingML, lxml * GIS Systems: Google Maps, OpenStreet Maps, Gisgraphy, Geocoding, Leflet, Mapbox, FusionTables, OpenLayers, Geonames * PHP: PHP5, PHP7 * MySQL: optimisation, speed up, complex queries * API's: design and various integrations: Quickbooks, Expedia, Highrise, Airtable, Zapier, Google and many more, * JavaScript, ECMA6, React.js, Canvas * Drupal: Drupal 7, Drupal 8 * Wordpress * Apache SOLR * Chess: Stockfish, * ImageMagick, * CRM, * OSTicket Businesses I am usually a good match for: * Sport: tennis, chess, ski, freeride, snowboard, gym, fitness * Travel: booking engines, travel websites To take this chat to the next level, here's what you should do next: Let's see if we're the right fit. If you're looking for a tailored IT system for your business and a developer that will bring you a productivity boost and more results, we're aligned. To get the conversation started, hit the Hire Now button in the top-right corner. P.S. I travel a lot. No matter what country you are from, feel free to reach out - I may already know how to say 'hello' in your language! :) Jacek Francuz

I’m Klaviyo Certified Email Marketer. I have 3+ years of hands-on experience in Klaviyo Email Marketing, and have generated $1M+ in revenue for ecommerce brands through Email and SMS. DM me for a free email design + audit 📈 $1M+ revenue generated through Email & SMS 📈 3+ years working inside Klaviyo for ecommerce brands 📈 Consistently generating 30-50% of my clients revenue from emails 📈 Served 30+ ecommerce brands across wellness, beauty, apparel, lifestyle, and CPG I help Shopify and Ecommerce brands across the US, UK, Europe, and other global markets build high-converting email and SMS systems inside Klaviyo. From core flow setup to advanced segmentation, campaigns, popups, and account optimization, I help brands increase repeat purchases, improve retention, and drive more revenue from the traffic they already have. A few recent results I've generated: 📈 Elephant Living: €386K from email in 60 days, 63% of total revenue 📈 Hund Hund: £59K in 30 days from email alone 📈 Moss Way: £30.8K/month, with email driving 48% of total revenue 📈 Helped brands grow email and SMS into 20 to 40% of total store revenue What I can help you with: ✅ Klaviyo Audits I review your current setup, find missed opportunities, and identify what to fix, improve, or build next. ✅ Klaviyo Setup Starting from scratch? I can provide expert Klaviyo Email Marketing so it is ready to support growth. ✅ Klaviyo Email Flows I build and optimize revenue-focused flows such as: Welcome Series, Abandoned Cart, Abandoned Checkout, Browse Abandonment, Site Abandonment, Post-Purchase, Review Request, Replenishment, Winback. ✅ Klaviyo Email Marketing Campaigns I execute data-backed Klaviyo Email Marketing for Shopify launches, promotions, Figma-designed emails, and retention. ✅ Segmentation I build useful segments so your Klaviyo Email Marketing is targeted, relevant, and profitable. ✅ Popups & List Growth I help improve subscriber capture with better forms, offers, and signup strategy. ✅ SMS Marketing I can help connect SMS with your wider retention strategy so email and SMS work together. ✅ Deliverability & Optimization If your metrics drop, specialized Klaviyo Email Marketing can help improve list health, sending strategy, and overall account performance. ✅ Strategy & Consulting If you need clarity on what to prioritize, I can help map out the biggest revenue opportunities inside your retention system. What working with me looks like: ⚡ Strategy first, not random execution ⚡ Brand-aligned emails, not generic templates ⚡ Clear communication throughout the project ⚡ Strong focus on revenue, retention, and customer experience ⚡ Hands-on execution inside Klaviyo I personally handle the strategy, copy, creative direction, and Klaviyo implementation. You are not hiring someone who only builds emails. You are hiring someone who understands how retention marketing should work from end to end. 🚫 My approach ⚡ No recycled templates that make your brand look like everyone else ⚡ No sending for the sake of sending ⚡ No generic best practices pasted across every account ⚡ The focus is always on what will actually improve performance 🛠 Platforms ✅ Klaviyo ✅ Omnisend ✅ Shopify ✅ Figma ✅ WooCommerce 📩 How you can work with me? Click “Invite” and send over a details about your brand, goals, or Klaviyo account. I keep my client roster focused so I can stay hands-on with every project. I’m open to both one-time Klaviyo projects and ongoing monthly support. I can also create a sample email mockup for your brand so you can see the fit before we start. 🤔 FAQs Do you only take one-time projects? No. I work on both one-off builds and ongoing retainers. Do you only work with Shopify brands? Mostly, yes. My main focus is ecommerce and DTC brands, especially those using Shopify and Klaviyo. Do you handle the strategy as well as the execution? Yes. I handle strategy, copy, creative direction, and implementation inside Klaviyo. Can you improve an existing Klaviyo account? Yes. A lot of my work is optimizing accounts via Klaviyo Email Marketing that already have flows or campaigns in place but are underperforming. Do you also help with SMS? Yes. I can help integrate SMS into your wider retention setup. Can you audit my account first before we start? Yes. I can review your setup and identify the biggest opportunities first. How do I get started? Send me an invite with a note about your store, current setup, or goals. Klaviyo Expert | Klaviyo Specialist | Omnisend | Klaviyo Email Flows | Klaviyo Email Automation | Klaviyo Flows Setup | Klaviyo Automation Specialist | Klaviyo Campaigns | Klaviyo Abandoned Cart Flow | Klaviyo Welcome Series | Klaviyo Segmentation | Klaviyo A/B Testing | Klaviyo SMS Marketing | Klaviyo Email Design | Klaviyo Email Templates | Klaviyo Pop-ups | Klaviyo Migration | Klaviyo Audit | Klaviyo Optimization | Klaviyo Shopify Integration | Klaviyo DTC Brands | Klaviyo Email Strategy | Klaviyo Email Marketing

Joshua Berk collaborates with innovative, daring people who seek to use technology for the benefit of the world in profound and meaningful ways. Previously, he worked at Google and J.P. Morgan, and has been consulting with startups (via the Techstars global startup ecosystem) for 10+ years. His specialties are distribution strategy, branding, design, marketing, and technology selection. He has advised more than 800+ businesses (including 30+ venture-funded startups) on go-to-market strategy. ✓ SEM / PPC: AdWords, Keyword Research, Bing ✓ Analytics: Tag Manager, Server-Side Tracking (SST) ✓ Display: Performance Max, Demand Generation ✓ Compliance: Cookie Consent, GDPR, CCPA, etc. ✓ Platforms: WordPress, Squarespace, Shopify, Zapier ✓ Video: YouTube In-Stream, Shorts, Bumper Ads ✓ Shopping: Merchant Center, Dynamic Remarketing ✓ Reporting: HubSpot CRM, CallRail, GA4 Goals ✓ Services: Google Ads Account Management Please note that I don't do white-label projects for agencies - thank you! 😄👍

I build mobile and web apps that feel fast, reliable, and easy to use — whether native mobile apps (Kotlin for Android, Swift for iOS), cross-platform apps (Flutter, React Native), or modern web applications (React, Next.js, Node.js). My goal is to make your product run smoothly, scale easily, and grow with your business. With a Ph.D. in Computer Science and 10+ years of development experience, I've successfully delivered 90+ iOS, Android, and web applications on Upwork — including custom solutions for logistics, healthcare, booking, education, and business automation. 💡 What I Do Best - Cross-platform mobile app development with Flutter & React Native - Native Android app development using Kotlin - Native iOS app development using Swift - Web application development with React, Next.js, and Node.js - Design of clean, maintainable architecture with scalability in mind - Integration of REST APIs, Firebase, AWS, and Supabase - Support for offline mode, background services, and push notifications - Performance optimization, UX improvements, and deployment (App Store, Google Play, web hosting) 🧠 Why Clients Choose Me I combine strong technical expertise with a product mindset — not just delivering code, but building reliable, user-friendly products that support long-term growth. Whether you're building an MVP or scaling an existing application, I can help you choose the right tools and technology stack for both mobile and web. 💬 Let's Build Something Solid If you're looking for a developer who covers both mobile and web ecosystems, let's discuss your next project.

Hi, I'm Khadija, a Top Rated Plus freelancer with 4,500+ hours worked, 100% Job Success Score, and extensive experience helping businesses with lead generation, prospect research, data entry, and data management projects. I specialize in both Lead Generation and Data Entry, so whether you need verified B2B contacts, prospect research, CRM updates, Excel/Google Sheets work, or large-scale data cleanup, I can provide reliable support from start to finish. My services include: ✔ Lead Generation ✔ B2B Lead Generation ✔ Prospect List Building ✔ Data Entry ✔ Data Mining ✔ Data Extraction ✔ Data Collection ✔ Data Cleanup ✔ Web Research ✔ Online Research ✔ Company Research ✔ Contact & Email Research ✔ LinkedIn Research ✔ Market Research ✔ CRM Data Entry & Management ✔ Microsoft Excel & Google Sheets ✔ PDF to Excel/Word Conversion Why work with me? ✓ Accurate and verified data ✓ Fast turnaround time ✓ Strong attention to detail ✓ Clear communication ✓ Reliable project delivery ✓ Long-term support Whether you need targeted leads, verified contact information, web research, CRM updates, or large-scale data entry support, I am committed to delivering quality work and helping your business stay organized and grow efficiently. Let's discuss your project. Thank you, Khadija

I am a professional Shopify Website Developer, working in this field for over 6 years. I have developed more than 100 Shopify websites so far. As well as I have a team who work on Web Design/UX/UI and website Management. SO I am a full package from website design, development to Maintenance. What I Do (End-to-End) ✔ Store Setup & Redesign – Shopify/Shopify Plus, OS 2.0, mobile-first UX ✔ Theme Customization & Liquid – custom sections, metafields, dynamic content ✔ Speed & SEO – Core Web Vitals, image optimization, schema, redirects ✔ CRO & Enhanced PDPs – product page layouts, bundles, upsells, A/B ideas ✔ App Integrations – Klaviyo, Judge.me, Recharge, PageFly/Gempages, Wishlist, Reviews ✔ Payments, Shipping, Taxes – compliant checkout settings, Markets (multi-currency/language) ✔ Data Migration – products, customers, orders; CSV & design migration ✔ Analytics & Tracking – GA4, Pixel, server events, conversion APIs ✔ Sales Channels – Amazon/eBay/Walmart/TikTok/Facebook & Instagram Shop connections ✔ Ongoing Management – updates, backups, bug fixes, landing pages, campaigns Process That Works Discover → Plan → Wireframe/Design → Build (Liquid/Sections) → QA & Speed → Launch → Support Clear milestones, proactive communication, and concise progress reports. More details services I provide for Shopify website development: 🎯 Web Design/UX/UI 🎯 Shopify Store Development with Mobile Compatibility/Responsive Web Design 🎯 Shopify Theme Customization 🎯 Custom Liquid Coding for The Website Presentation and Layout 🎯 3rd Party Apps Integration & Configuration 🎯 Shopify Website Domain Integration & Support 🎯 API integration 🎯 Data and Design Migration Service 🎯 Shopify Store Optimization 🎯 Enhanced Product Page 🎯 Payment, Shipping, Tax Set Up 🎯 Integrate Mailchimp or Klaviyo to Manage The Customer Login Information 🎯 Integrate Google Maps on Your Shopify Website 🎯 Any Type of Sales Channel Integration Like Amazon, Ebay, Walmart, etc. 🎯 Apps integration like Facebook, Instagram, Twitter etc. 🎯 Instagram feed integration with Shopify 🎯 Other apps integration like google channel, pinterest, Data Migration, Product Reviews, Shopify Inbox etc. 🎯 Website SEO 🎯 Shopify Listing or Account Management 🎯 Bulk Data Processing ( Listing Upload or Update Via Csv File ) 🎯 Order Management and Fulfillment, Customer Services Shopify is certainly the most technical-friendly eCommerce platform with a fully customizable theme. So far I have developed 100+ Shopify eCommerce websites, which are doing well in the eCommerce world. Our Unique Stargary to Success Road Map 🎯Understanding Your Requirements 🎯Creating a Roadmap 🎯UI/UX Design 🎯Client Confirmation 🎯Design Development 🎯Testing and Quality Assurance 🎯Deployment and Launch 🎯Support 🎯After-sales Management, SEO and Marketing With all that experience, It will be very feasible for me to develop your Shopify website and manage all your store data. My main focus is to achieve your business goals in terms of Sales and Profitability. For better sales and business growth, I do not start immediately after having a project on my hands. I work step by step. First, I review the project, look for possibilities and limitations, and create a proper plan. Then share the plan with the client. After getting positive feedback from my client, I execute the plan for the project. What differentiates me: * Skilled Shopify Professional Team * Free Website Audit * Mobile Responsive / Compatibility Web Design * Shopify App Integration and Bug Fixing * Custom Product Page or Landing page development * Payment setup and domain integration * Shopify Custom section development * Work ethics and professionalism * Commitment and Deadline maintaining the mentality * Reporting style to know exactly where I stand * Goal oriented * Productive Communication Looking forward to communicating and discussing it with you in detail. Because communication is very important. Lack of communication can cause failure. To create the most effective outcomes for our client's projects, we try to avoid confusion through productive communication and understanding. We can arrange a Zoom/meet call or your preferred online platform for further discussion. Looking forward to communicating and discussing it with you in detail.