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🟢 AVAILABLE TODAY, 07.07 ⚡ Message me "AUDIT" - get a free 30-min technical review of your app idea, architecture, or existing codebase. No sales pitch. Just honest engineering feedback. I'm Siarhei - ex-CTO × 3 funded startups, CEO of Sparkler Soft. We build native iOS & Android products that ship, scale, and raise. 🔵 PROVEN RESULTS ◈ iHairium - AI Hair Diagnostics (live on App Store) Neural network · 100K+ training images · 95-98% accuracy $600K angel round + $5M seed valuation Revenue ×10 to ×1000 per month in early stages Google & Amazon grants · 1,000+ clinic partners onboarded ◈ Eco-Go - Electric Scooter Sharing Platform iOS + Android + Backend + IoT + Admin Panel AWS IoT Device Management · Swappable battery infrastructure Named "Best Startup of the Region" ◈ Optics Platform [White-label · Strict NDA] AI-assisted frame & lens selection via device camera Active in 60+ countries · 1,000+ fitting points worldwide 10+ years on market · Award-winning at international exhibitions ◈ Chibbis - Unified Food Delivery Service 600+ restaurants · 150+ cities across Russia iOS + Android + Web + Admin Panel + CMS One of the country's leading delivery platforms ◈ CoinForShop - Crypto Marketplace iOS + Android + Web (React) Non-custodial wallets · Smart contract payments BTC · ETH · BCH · LTC · XMR · TRX · 100% MVP delivered ◈ Azarium - NFT Real Estate Investment Platform Fractional property ownership via blockchain MAS-regulated · Live construction webcam in-app Min investment from $200 · Expected ROI 30–60% 🟠 WHAT WE BUILD → HealthTech & AI On-device ML · Camera diagnostics · Neural networks TensorFlow Lite · Core ML · OpenCV → FinTech & Crypto Wallets · KYC/AML · Stripe · Smart contracts · NFT → Mobility & IoT GPS · BLE · AWS IoT · Scooter & bike sharing Telematics · Real-time fleet management → Marketplace & Delivery Full-stack: app + backend + admin panel + CMS → API Integrations Stripe · Mapbox · Sumsub · Firebase · any third-party 🟡 TECH STACK Mobile: Swift · SwiftUI · Objective-C · Kotlin · Java Backend: Java Spring Boot · Node.js · NestJS · Golang Frontend: React · Next.js AI/ML: TensorFlow Lite · Core ML · OpenCV Cloud: AWS · GCP · Azure · Docker · Kubernetes · CI/CD Data: PostgreSQL · MongoDB · Redis · Elasticsearch Security: OAuth2 · OIDC · JWT · Keycloak · Biometrics · IAP 👉 Message "AUDIT" right now - 30 minutes to understand if we're the right fit. No obligation. No pitch. Just clarity.

📌 Need a reliable Java developer who can take your system from idea to deployment—fast, clean, and scalable? I’ve been doing exactly that for 14+ years as a Java Spring Boot Developer. As a senior Java Spring Boot Developer, I help businesses build high-performance, cloud-native applications using Java Spring Boot, microservices architecture, and modern engineering practices. Whether you need a Spring Boot developer, a backend architect, or a hands-on Java developer, I bring both technical depth and product thinking. I specialize as a Java Spring Boot Developer in building modular, scalable, and cloud-ready systems. As a Spring Boot developer, I design clean architectures for Java microservices, real-time systems with Kafka or RabbitMQ, and high-load applications. As a Java developer, I ensure systems are maintainable, testable, and optimized for long-term growth. Working as a Java Spring Boot Developer, I frequently collaborate with frontend teams using Spring Boot React and Spring Boot Angular stacks. As a Spring Boot developer, I align backend logic with frontend needs, ensuring smooth integration across JavaScript, HTML CSS JavaScript, and UI layers. My experience as a Java developer also includes working with JavaFX interfaces when needed. Cloud is a key part of my work as a Java Spring Boot Developer. I’ve deployed scalable systems on AWS and GCP, acting as both AWS and GCP architect. As a Java developer, I work with AWS DevOps tools like Lambda, API Gateway, Cognito, S3, and EC2. As a Spring Boot developer, I integrate backend services with GCP tools such as Firestore, Pub/Sub, and Cloud Functions, ensuring performance and reliability. Databases are another strong area. As a Java developer, I’ve worked with PostgreSQL, MySQL, SQL Server, Oracle, MongoDB, and Cassandra. As a Spring Boot developer, I design efficient schemas, optimize queries, and handle large-scale data systems. Every Java Spring Boot Developer project I take on includes a strong focus on database performance and scalability. Clean code and testing are essential in my workflow as a Java Spring Boot Developer. I rely on JUnit testing, TDD, and CI/CD pipelines. As a Java developer, I use Maven, Docker, GitHub Actions, and Jenkins to ensure stable delivery. As a Spring Boot developer, I focus on building systems that are reliable, testable, and easy to extend. 📊 Snapshot of My Expertise 💻 Delivered 20+ systems as a Java Spring Boot Developer, including fintech platforms and SaaS applications ☁️ Worked as a Java Spring Boot Developer and cloud architect using AWS and GCP infrastructure 📊 Optimized large-scale databases as a Java developer, improving performance by up to 60% 🔁 Built intelligent systems integrating Spring AI as a Spring Boot developer 🔐 Secured APIs using OAuth2 and Hibernate as a Java Spring Boot Developer 🧪 Maintained high test coverage using JUnit and CI pipelines as a Java developer 🧰 Collaborated across teams delivering full features as a Spring Boot developer If you’re looking for a Java Spring Boot Developer, a reliable Java developer, or an experienced Spring Boot developer who can handle complex systems and deliver scalable solutions I’m ready to help. 📩 Send me a message I usually reply within a few hours.

I’ve successfully completed multiple projects on Upwork with 5-star ratings and positive client feedback. If you’re facing any kind of tech-related problem, I’m here to help. I specialize in backend development, frontend development, and database management. Over the years, I’ve built projects such as: ✅Enterprise Multi-Tenant SaaS POS Application ✅Expense Tracker ✅Food Delivery Web App ✅Smart Pharmacy Management System ✅Retail Billing Software ✅Trading Platform ✅Book Rental System ✅Hospital Management System Previously, I worked as a Junior Backend Developer, where I created REST APIs, fixed bugs, collaborated with frontend developers, and managed databases. Working remotely strengthened my communication skills and taught me how to coordinate effectively with distributed teams. Technical Skills ✅ Languages: Java, JavaScript, Python ✅ Frameworks: Spring Boot, Spring MVC, Hibernate, React, Tailwind CSS ✅ Web Services: RESTful APIs ✅ Databases: MySQL, PostgreSQL, MongoDB ✅ Tools: VS Code, IntelliJ, Eclipse, Postman, Git/GitHub ✅ Frontend: HTML5, CSS3, JavaScript ✅ Practices: Git-based version control, Agile methodology, automated testing What I Can Do for You ✅ Develop and maintain RESTful APIs with Java & Spring Boot ✅ Design scalable and efficient backend architectures ✅ Build dynamic, responsive web interfaces with React, Tailwind CSS, HTML, and JavaScript ✅ Integrate relational databases and ensure data integrity ✅ Debug and fix performance or functional issues across the stack ✅ Collaborate with frontend, backend, and mobile teams for end-to-end solutions ✅ Deploy applications and assist with basic DevOps tasks I believe in clear, friendly communication to keep projects running smoothly and ensure we’re always aligned. Let’s chat about your project and see how I can help bring it to life! “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler

Java Spring Developer with over 15+ years of experience building scalable, high-performance solutions across diverse industries. Technical Expertise ✅Spring Ecosystem: Spring Boot, Spring Batch, Spring Cloud, Spring Security, Spring AOP, Spring MVC, JSP, Thymeleaf. ✅ AI : Claude , Codex , RAG ,Integration with OpenAI ✅Microservices & APIs: Microservices architecture, RESTful APIs. ✅Messaging & Event-Driven Systems: Apache Kafka, WebSocket, STOMP, Socket IO ✅Cloud Integration: AWS (ECS Fargate, S3, EC2, ALB, RDS). ✅Database Design: SQL (MySQL, Oracle, Yugabyte, PostgreSQL, MS SQL Server) ✅DevOps & Containers: CI/CD pipelines, Jenkins, Docker, Podman, Kubernetes ✅Search & Caching: Elasticsearch, Redis, Terracotta Caching ✅System Integration & Legacy Modernization: Seamlessly integrate modern applications with legacy systems ✅Frameworks & Tools: JHipster, Keycloak, Flowable, JBPM, Flyway, MapStruct, JavaFX, Java Swing ✅CMS Solutions: Documentum, Alfresco ✅XML & Web Services: SOAP, RESTful services ✅Reporting Tools: Crystal Reports, JasperReports, BIRT ✅Testing Framework/Tools: Junit5,Selenium,JMeter

𝗝𝗮𝘃𝗮 𝗕𝗮𝗰𝗸𝗲𝗻𝗱 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 🖥️, 𝗦𝗽𝗿𝗶𝗻𝗴 𝗕𝗼𝗼𝘁 🌱, 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀 🛠️, 𝗔𝗪𝗦 ☁️, 𝗥𝗘𝗦𝗧 𝗔𝗣𝗜𝘀 🔗 I help businesses build scalable, secure, and high performance backend systems that handle growth without slowing down. Most applications work well in the beginning. The problems start when traffic increases. APIs become slow, deployments become risky, and maintaining the code becomes expensive. That's where I come in. 𝗔𝘀 𝗮 𝗦𝗲𝗻𝗶𝗼𝗿 𝗝𝗮𝘃𝗮 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 𝘄𝗶𝘁𝗵 𝟭𝟯+ 𝘆𝗲𝗮𝗿𝘀 𝗼𝗳 𝗲𝘅𝗽𝗲𝗿𝗶𝗲𝗻𝗰𝗲, I've helped startups and enterprise companies design, build, and optimize backend systems that scale reliably in production. I am not just a Java Developer who writes code. I help businesses create backend architectures that support growth, improve performance, and reduce technical debt. 𝗥𝗲𝘀𝘂𝗹𝘁𝘀 𝗜'𝘃𝗲 𝗗𝗲𝗹𝗶𝘃𝗲𝗿𝗲𝗱 • Built scalable Java Developer solutions serving thousands of daily users with high availability. • Designed Microservices architectures that reduced deployment risks and improved system reliability. • Developed Spring Boot applications that improved API response times and backend performance. • Helped businesses migrate legacy systems into modern Java Developer architectures. • Delivered production ready backend platforms for startups and enterprise organizations. Every project starts with a business goal and ends with measurable results. 𝗪𝗵𝗮𝘁 𝗜 𝗗𝗼 𝗝𝗮𝘃𝗮 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 • Custom backend application development • Enterprise Java solutions • Legacy application modernization • Backend performance optimization • Secure and maintainable architecture 𝗦𝗽𝗿𝗶𝗻𝗴 𝗕𝗼𝗼𝘁 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 • REST API development • Spring Security • Spring Data JPA • Authentication and authorization • Scalable backend services 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀 𝗔𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲 • Distributed systems design • Service decomposition • API Gateway implementation • Event driven architecture • System scalability and resilience 𝗔𝗪𝗦 𝗖𝗹𝗼𝘂𝗱 𝗦𝗼𝗹𝘂𝘁𝗶𝗼𝗻𝘀 • AWS deployment and infrastructure • EC2, ECS, Lambda • Cloud architecture design • Monitoring and optimization • Cost effective cloud operations 𝗥𝗘𝗦𝗧 𝗔𝗣𝗜 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 • API design and implementation • Third party integrations • Payment gateway integration • Documentation and testing • Secure API architecture 𝗪𝗵𝗮𝘁 𝗠𝗮𝗸𝗲𝘀 𝗠𝗲 𝗗𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝘁 Most Java Developers focus only on writing code. I focus on the business impact of the software. 𝗕𝗲𝗳𝗼𝗿𝗲 𝗯𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝗮𝗻𝘆𝘁𝗵𝗶𝗻𝗴, 𝗜 𝗮𝘀𝗸: • Will this architecture still work when traffic grows? • Can future developers maintain it easily? • Is it secure? • Is it optimized for performance? • Can it scale without major rewrites? This approach helps clients avoid costly problems later. 𝗪𝗵𝗼 𝗜 𝗪𝗼𝗿𝗸 𝗕𝗲𝘀𝘁 𝗪𝗶𝘁𝗵 • Startups building new SaaS products • Businesses scaling existing applications • Companies modernizing legacy Java systems • Teams adopting Microservices architecture • Organizations migrating workloads to AWS • Businesses needing secure and scalable REST APIs 𝗧𝗲𝗰𝗵𝗻𝗼𝗹𝗼𝗴𝗶𝗲𝘀 Java, Spring Boot, Spring Security, Hibernate, JPA, Microservices, AWS, Docker, Kubernetes, REST APIs, Kafka, RabbitMQ, PostgreSQL, MySQL, MongoDB, Redis, Maven, Gradle, Git, CI/CD, Jenkins 𝗪𝗵𝘆 𝗖𝗹𝗶𝗲𝗻𝘁𝘀 𝗛𝗶𝗿𝗲 𝗠𝗲 • 13+ years of Java Developer experience • Clean, maintainable code • Scalable backend architecture • Strong communication • Reliable delivery • Long term technical thinking If you're looking for a Java Developer who understands both software engineering and business objectives, let's discuss your project. Send an invitation and I'll respond within a few hours. Keywords: Java Developer, Senior Java Developer, Java Backend Developer, Java Software Engineer, Spring Boot Developer, Spring Boot Expert, Java Application Development, Enterprise Java Developer, Java Web Services, REST API Developer, RESTful API Development, Backend Developer, Backend Engineer, Microservices Developer, Microservices Architecture, Distributed Systems, AWS Developer, AWS Cloud Engineer, Java AWS Developer, Docker, Kubernetes, Kafka, RabbitMQ, Hibernate, JPA, Spring Security, API Integration, Database Design, PostgreSQL, MySQL, MongoDB, Redis, SaaS Backend Development, Scalable Application Development, Cloud Native Applications, Java Consultant, Software Architecture, System Design, Enterprise Application Development, Performance Optimization, CI/CD, Jenkins, Maven, Gradle, Full Stack Java Developer.

I am an ACM-ICPC World Finalist and software engineer. I have been developing backend and DevOps solutions using C++, Java, and Python since 2016. I have experience in multiple domains that include fintech, agrotech, health tech, IoT, and Saas. I have been working as a remote developer with globally distributed teams since 2019. I am a quick learner, good with communication, proactive and punctual human being. Nothing excites more me than a challenge that is necessary but difficult to solve. I am also a competitive programmer and expert in data structures and algorithms. I have a decent understanding of UNIX systems especially how different types of data structures are blended to solve complex problems of operating systems. I am a team player and can work as solo as well. I never compromise the quality of my work doesn't matter how the pressure is. And, I believe in requirement analysis as the most crucial part of engagement.