Hire the Best Payment Gateway Integration Specialists
in Poland

Looking for a functional website that actually works for your business? Let’s build it. I don’t just "click buttons" in builders - I create complete digital ecosystems. Whether it’s a high-converting dropshipping store on Shopify or a complex dynamic site on WordPress, I focus on performance, clean design, and marketing readiness. What I bring to the table: 🚀 Shopify Excellence: I build ready-to-launch stores in 3-5 days. My expertise includes: Full Store Setup: From theme customization to payment gateway integration (Przelewy24, Shopify Payments, Stripe, PayPal). Dropshipping Automation: Seamless integration with Zendrop, CJ Dropshipping and DSers. Marketing Stack: Setting up Meta Pixel, Klaviyo (email flows), and Smartlook to track your customers' behavior. 🎨 WordPress & Advanced Functionality: I create professional business websites using Elementor Pro and advanced tools for dynamic content: Custom Structures: Using JetEngine, ACF (Advanced Custom Fields), and JetSmartFilters to build directories, booking systems, or complex catalogs. Performance: Clean builds that are easy for you to manage after hand-over. Landing Pages: High-speed pages designed to convert visitors into leads. Why work with me? Business Mindset: I understand that a website is a tool for making money, not just a pretty picture. Fast Turnaround: Your Shopify store can be ready for its first customer in less than a week. No-Code Flexibility: I build sites that you can easily edit yourself without hiring a developer for every small change. Currently based in Poland, working with clients across Europe and Ukraine. Let’s hop on a quick chat to discuss your project!

Need a Laravel or Symfony developer who can build SaaS billing that actually survives production? I specialize in Stripe subscriptions, multi-tenant architecture, and long-term infrastructure maintenance — from the first checkout to year-three scaling. I build and maintain high-load SaaS platforms where payments and billing cannot afford to fail. If you're launching a subscription product, scaling a multi-tenant ecosystem, or you've inherited a complex legacy codebase that needs a reliable hand — that's exactly what I do. 🎯 Core Areas of Expertise 💳 Stripe & Subscription Systems Full subscription lifecycle management: asynchronous webhooks handling, metered billing, upgrades/downgrades, dunning management, and Stripe Connect for marketplaces. 🏢 Multi-Tenant SaaS Architecture Robust tenant isolation strategies (single-database with scoped scopes or multi-database systems), dynamic subdomains, and clean infrastructure boundaries using Docker and Caddy. 🏗️ Long-Lived Enterprise Systems Deep work with large-scale Laravel and Symfony applications using Domain-Driven Design (DDD). I design clean architectures that remain maintainable years down the road. 🔌 High-Performance APIs & Integrations Designing scalable REST and GraphQL backends optimized for high concurrency, webhooks processing, and clean consumption by frontend layers. 🔐 Security & Data Resilience Encryption at rest, strict Role-Based Access Control (RBAC), secure OAuth/token authentication, and automated backup strategies. 🛠️ Legacy System Takeovers & Maintenance I don't just patch symptoms; I audit and fix the root cause. If you have a fragile, unoptimized application that frequently drops connections, chokes on database queries, or fails during high-traffic windows, I step in to modernize the code, optimize the infrastructure, and stay on as your long-term tech partner. 📊 Proven Track Record 8+ years of engineering production-grade PHP systems (Laravel, Symfony, Go). 2,000+ logged hours on Upwork with a flawless 5-star rating across all contracts. Consistent history of long-term, multi-year client partnerships — not just one-off gig builds. Expert workflow utilizing cutting-edge tools (Docker, PHPStorm, PHPStan, Pest, Claude Code) for automated quality control and rapid deployment. I read your codebase thoroughly before making a single change. I communicate clearly, document everything, and never disappear mid-project. If you are looking for a reliable, product-minded engineer to take your platform to the next level, send me a message. Let’s jump on a quick call, audit your current challenges, and outline a concrete roadmap.

🚀 **Back End Developer and Integrations Specialist** I am a highly skilled Senior Back End Developer and DevOps professional. My expertise spans cloud deployments, web development, and data analytics, bringing innovative and scalable solutions to every project. 🌐 **Web Development and AI Integration Expertise:** With over 6 years in IT system analysis and 2 years focusing on web development, my skillset includes: - **Backend Development**: Crafting efficient, scalable backend systems using Python, Django, Fast and RESTful APIs. - **AI and Automation**: Building advanced AI-powered solutions, and integrating AI API to enhance decision-making processes. - **Web Scraping & Data Collection**: Extracting valuable insights with tools like Selenium, BeautifulSoup, and Requests for accurate, real-time data gathering. 🌟 Key Strengths: *Kubernetes and Docker: Expertise in containerization and orchestration, ensuring seamless deployment and management of applications. *Terraform: Skilled in infrastructure as code, automating and optimizing cloud infrastructure with best practices. Cloud Platforms: Extensive experience across AWS, delivering scalable and secure cloud solutions. CI/CD Tools: Proficient in CI/CD pipelines using YAML, GitHub Actions, and GitLab CI for continuous integration and deployment. Monitoring Tools: Familiar with Grafana, and AWS Cloud Watch, ensuring effective monitoring and performance optimization. 🔧 **Tech Stack:** ✔Programming languages: Python, CSS, HTML ✔UI UX Tools: Figma, Framer, WixStudio ✔Blockchain: KYC, Payment Gateway integration ✔Front-end Technologies: HTML5, CSS3, Bootstrap, jQuery ✔Development Frameworks: Django, Flask, FastAPI, RestFull ✔Databases: MSSQL, MySql, RDS, DynamoDB ✔Database Development: DjangoORM, AWS DynamoDB SDK ✔APIs: Facebook API, E-Commerce API, Twilio API, PostMan, PubMed, ClinicalTrials ✔Servers: Windows Azure, AWS, SQL Server ✨ **Why Choose Me:** With a blend of Backend development, Cloud and DevOps expertise, I deliver high-impact solutions that align with business goals. My problem-solving skills, combined with a collaborative mindset and a passion for innovation, set me apart in every project. ✨ Proven Track Record: Successfully delivered numerous projects, meeting and exceeding client expectations. 🎯 Client-Centric Approach: I prioritize understanding your business goals to deliver solutions that align perfectly with your objectives. 💼 Project Management: Proficient in the double triangle methodologies, ensuring projects are delivered on time and within budget, while keeping client satisfaction. 🌐Practical experience in analytics and support give me an advantage over other developers because I troubleshoot issues while keeping deadlines and productivity, putting together data that is relevant for business impact. 🚀 Let’s collaborate and drive your business forward with cutting-edge Cloud, AI, and Web development solutions!

Are you tired of average designs and looking for something to boost your business? Let's collaborate to create an exceptional user experience that meets and exceeds your expectations! My name is Darya, with more than 5 years of experience in web and graphic design I have completed 130+ projects. Transform your creative ideas and business objectives into stunning, high-performing digital platforms that not only meet but exceed industry best practices. In every project I follow simple steps: listen attentively to your vision, immerse myself in your goals, comprehend your unique challenges, and then craft the best solutions. ⭐️⭐️⭐️⭐️⭐️ — My clients say about me ⤵️ 💬 ""Daria was excellent on every front, shes a great communicator, she delivered quickly in less time than quoted and the webflow website was great. Really really worth hiring. By far my best experience on upwork! Thanks again Darya!" – Bertie, Web3 (UAE) 🌐 Technology I and my team use: 🛠 CMS: Shopify, WebFlow, Framer, WIX 🛠 Design: FIGMA | Adobe Photoshop | Adobe Illustrator | inVision | Spline ⛔️Stop wasting time on designers and developers who do not understand your tasks and true goals ✅ Click the "Invite" button at the top right corner of this page to start our journey together. In our cooperation, you'll have: 🔵 Goal-oriented strategies 🔵 A transparent work structure 🔵 Adherence to project estimates 🔵 Open and honest communication 🔵 Comprehensive reporting 🔵 Industry-specific best practices ✅ 𝐋𝐞𝐭'𝐬 𝐬𝐜𝐡𝐞𝐝𝐮𝐥𝐞 𝐚 𝐜𝐡𝐚𝐭 𝐰𝐡𝐞𝐫𝐞 𝐈'𝐥𝐥 𝐩𝐫𝐨𝐩𝐨𝐬𝐞 𝐚 𝐭𝐚𝐢𝐥𝐨𝐫𝐞𝐝 𝐬𝐭𝐫𝐚𝐭𝐞𝐠𝐲 𝐟𝐨𝐫 𝐲𝐨𝐮𝐫 𝐛𝐮𝐬𝐢𝐧𝐞𝐬𝐬 Best, Darya K. ___________ PS: Don't leave this page without clicking the '𝐈𝐧𝐯𝐢𝐭𝐞' button. It's a sign we should start talking about improving your business! Should you wish to collaborate or require further information, please don't hesitate to reach out. ✅ Keep in mind that investing in a well-crafted and lucid platform design can greatly benefit your business Updated: March 2026 🔑 you can find me via these keywords: UI/UX Design, UI Design, UX Design, Web Design, Landing Page Design, Graphic Design, User Experience Design, User Interface Design, Mobile UI Design, Responsive Web Design, High Fidelity Prototyping, Wireframing, Mockups, Design Systems, Style Guide, Branding, Website Redesign, Usability Testing, User Flow, Clickable Prototypes, Visual Communication, Responsive Design, User Research, Education Landing Page, EdTech Landing Page, Online Course Landing Page, LMS Design, Educational UI/UX, eLearning Platform Design, Course Signup Page, Learning Management System Design, Student Portal Design, SaaS for Clinic, Healthcare Landing Page, Medical Web Design, Telemedicine App Design, Patient Portal Design, Clinic SaaS UI, HealthTech UI/UX, Doctor Booking Page Design, Medical SaaS UI, HIPAA-Compliant Design, eCommerce Web Design, Shopify Store Design, WooCommerce Website, Product Landing Page, Shopify App UI, Shopping Cart UX, eCommerce App UI, Payment Gateway Integration, Product Catalog Design, Mobile-First eCommerce Design, SaaS Landing Page, SaaS Onboarding Flow, SaaS Product Page, SaaS Dashboard Design, Subscription Page Design, SaaS Web Design, B2B SaaS UI/UX, Pricing Page UX, CRM SaaS Design, Cloud Software UI/UX, Fintech App Design, Financial SaaS Platform, Banking App UI, Fintech Landing Page, Investment Platform UI, Payment Gateway Design, Digital Wallet UX, Wealth Management UI, Cryptocurrency Wallet Design, Real Estate Landing Page, Property Listing UI, Real Estate SaaS Design, Rental App Design, Property Management SaaS, Real Estate CRM, Agent Profile Design, Booking Page Design, Virtual Tour UI, B2B Landing Page, Consultancy Website Design, Lead Generation Page, Corporate Website Design, Enterprise SaaS UI, Professional Services Website, Client Onboarding UI, Sales Funnel Design, Service Page UX, Nonprofit Website Design, Donation Page Design, Charity Landing Page, Event Registration UI, Volunteer Portal Design, Cause-Based Landing Page, Fundraising Page UX, Advocacy Website UI, Travel Booking Page, Hospitality Landing Page, Tourism Website Design, Hotel Booking UI, Itinerary Planner UI, Flight Booking UX, Vacation Rental Design, Hospitality SaaS Design, WordPress Design, Shopify Design, WooCommerce Design, Squarespace Design, Wix Design, Webflow Development, Custom HTML Design, Midjourney, ChatGPT, AI Tool Integration, A/B Testing Tools, Marketing Automation Tools, User Analytics Integration, Google Material Design, Apple Human Interface Guidelines, iOS & Android Guidelines, Accessible Web Design

🏆 𝗧𝗢𝗣 𝗥𝗔𝗧𝗘𝗗 𝗣𝗟𝗨𝗦 🏆 ✅ Mobile App Developer 7+ years of experience ✅ SaaS Mobile App Developer 5+ years ✅ 35 mobile app development jobs completed successfully ✅ Android and iOS Mobile Expert ✅ Built 27+ UX-first Mobile App development jobs for 22 companies ✅ On-Time and Cost-Effective Delivery ✅ Future-Proof Solutions Showing a Minimum 41% ROI ✅ 4354 mobile app development hours on Upwork and still counting ✅ 100% Job Success in mobile app development (Client Satisfaction Ratio) ✅ 98% of Clients Recommended working with me ✅ 80% Long-term Repeat Clients ✅ 7+ years of experience in mobile app development, 6 years experience in iOS mobile app development, 7 years experience in Swift and Kotlin, 4 years experience in Flutter, React Native, 2 years experience in KMM, KMP Full stack mobile app developer and mobile app UI UX designer with 7+ years of experience in Mobile App Development, specializing in iOS, Swift, Android, Kotlin, KMM, Kotlin Mutliplatform / KMP, React Native, and Flutter. I have successfully delivered 120+ mobile applications in different roles as mobile app developer, flutter app developer, flutter full stack developer, flutter flow, mobile app design, mobile ui ux designer, swift ios developer, android developer, kotlin developer, react native developer, mobile game developer achieving a 5-star rating on Upwork and helping clients scale their businesses with high-performance solutions. Apart from mobile app development, I specialize in Mobile App Design for both iOS and Android, as well as Web App Design for SaaS platforms. My expertise extends to Interaction Design, User Flow Design, and creating seamless User Experience (UX Design) and User Interface (UI Design). I follow a Design Thinking approach, ensuring every solution is user-centered and problem-solving. My process includes UI/UX Wireframing, Prototyping, and building Style Guides or UI-kits for consistent branding. I perform Design Audits and Design QA to maintain high standards across all projects. 🛠️ Design Tools: My designs come to life through powerful tools like Figma, Zeplin, and InVision for prototyping and collaboration. I leverage Adobe Illustrator, Adobe Photoshop, and Adobe XD for detailed visual design. For complex wireframes and flow mapping, I turn to Axure, Sketch, and Balsamiq. I also use Miro and Abstract for brainstorming and version control, while project communication and management happen in Slack and Jira. Our Expertise at a Glance • Mobile App Development: Android, iOS, & Cross-Platform App Development using Java, Kotlin, Swift, Objective C, Flutter, and more. • Website and Full Stack Development: Crafting seamless back-end experiences with .Net, Python, Java, Javascript, React.js, Angular.js, Node.js, MERN, MongoDB, PHP, etc. • Logo & UI/UX Design: Bringing your ideas to life with Adobe XD, Photoshop, Sketch, Figma, etc. • End-to-End Solutions: From logo design, UI/UX development, workflow setup, testing to deployment in app stores, we've got it all covered. We do not use v0.dev lovable.app CursorAI, Cursor, Windsurf, Trae, GitHub Copilot, Tabnine, Qodo, Devin AI, and AutoDev for speed up coding, we know other methods to do it efficiently. We offer a comprehensive range of development services across mobile, web, and cloud platforms. Our mobile app development expertise includes building Android and iOS applications using technologies such as Flutter, Swift, Objective-C, React Native, and Xamarin, optimized for both smartphones and tablets with a focus on cross-platform compatibility. In website and full stack development, we work with .NET technologies, including full stack .NET development, .NET Core, and Python with Django. Our team is experienced in developing both backend systems and user-friendly, responsive web interfaces, as well as working with various CMS platforms. Our DevOps and DevSecOps capabilities cover cloud infrastructure and automation, leveraging tools like AWS, Azure, Docker, Kubernetes, GitLab CI, Ansible, and Terraform to build secure and scalable deployment environments. We also build cross-platform and web applications using frameworks like Three.js and design tools such as Webflow, creating visually engaging and functional user experiences across devices. Additionally, we are well-versed in integration and automation tools, including WebSockets, data integration, the ABP Framework, Discord API, and Autotask, allowing us to create seamless connectivity and workflow automation between systems. Talent Good Knowledge, Talented, Experienced, Skilled, Strong Experience, Proven Experience, Agency, Team, Company, Specialist, Proven Track Record, Strong Background, Write Clean Code, Deep Expertise, Bring to Life, Cross-platform, Attention to Detail, Long Term. ⚡️ AVAILABLE FOR NEW PROJECTS ⚠️ Press Invite Button on my page and let's talk.

Summary Have experience in medium and small projects support. Can develop new features, rest api connections, fix bugs, make code optimization. Have an ongoing project under maintenance which was built from scratch - Laravel-based multi-tenancy SaaS platform with multiple APIs integrations (can send link by request). Every day I learn something new and hone existing skills. I know my abilities and do not take work that I can not complete. Primary technologies used: - backend: Php, Laravel, Codeigniter, Wordpress. - databases: Mysql. - frontend: Javascript, Vue, Html, Css/Sass, Bootstrap. Additional areas: Server administration (Ubuntu, Nginx).