💼 Profile Overview I am a senior Java backend engineer with deep experience building reliable, scalable, and cleanly architected systems for production environments—especially in telecom, enterprise platforms, and transactional systems. For the past several years, I’ve worked extensively with Java (8+) and Spring-based applications, focusing not just on “making things work,” but on designing systems that are maintainable, testable, and future-proof. I have a strong preference for clean code, solid abstractions, and proven design patterns (Template Method, Strategy, Chain of Responsibility, DDD-inspired architectures). 🔧 What I specialize in Java backend development (Java 8+, Spring / Spring Boot) System & API design (REST, SOAP, CXF, integrations) Complex business logic & refactoring of legacy code Concurrency & performance (parallel processing, batching, locking, race-condition prevention) Database-heavy applications (PostgreSQL, JPA/Hibernate, CriteriaBuilder, query optimization) Enterprise integrations (SOAP/WSDL, government APIs, fiscalization systems) Asynchronous & event-driven patterns (Inbox/Outbox, eventual consistency) Testing & reliability (unit tests, concurrency tests, clean test isolation) 🧠 How I work I don’t just implement tasks blindly—I analyze the problem domain, ask the right questions, and often propose simpler or more robust solutions than originally planned. Clients appreciate that I: Refactor duplicated or fragile code into clean, reusable components Spot architectural risks early Write code that other developers can actually understand Balance correctness, performance, and long-term maintainability 🏗️ Real-world experience Telecom-grade systems handling subscription lifecycles, synchronization, and high concurrency Enterprise APIs with strict validation, error handling, and audit requirements Custom frameworks and internal libraries (including Maven plugins and Java libraries) Docker-based environments, multi-module Maven projects, and CI-friendly setups 🎯 Ideal projects I’m a great fit if you need: A senior Java engineer who can own backend logic end-to-end Help refactoring or stabilizing a complex Java/Spring codebase Someone to design or improve architecture, not just write features Clean integration with external systems (SOAP/REST, legacy or modern) If you value clear communication, strong technical judgment, and production-quality code, I’d be happy to work with you.

Hi, I'm Hasitha, a software engineer having extensive experience of over 7 years in software and web development, server administration and also a strong communicator with the ability to convey ideas clearly with an emphasis on client satisfaction. My specialized areas are as follows. ◈ Server-related tasks ✅ Troubleshooting issues related to web servers (Apache, NGINX). ✅ Installation/renewal of SSL certificates. ✅ Troubleshooting Linux server-related issues. ✅ Configuration of LAMP/LEMP stack. ✅ Fixing 401, 403, 404, 502, and 503 HTTP errors. ✅ Configuration of Webmin, Virtualmin, WHM, and cPanel. ✅ Troubleshoot SSH access-related issues. ◈ WordPress websites ✅ Migration of WordPress websites from one hosting to another ✅ Troubleshooting WordPress website-related issues (Critical errors, outgoing emails not working, etc.). ✅ Set up SMTP email configurations. ✅ WordPress core, themes, and plugin updates. ✅ Payment gateway integrations. ◈ Email related configurations ✅ Google Workspace email set up. ✅ SMTP configurations for different web applications. ✅ Configuration of third-party SMTP providers such as AWS SES, SendGrid. ◈ DNS related tasks ✅ Configuring DNS (adding/modifying DNS records, updating nameservers) in different domain providers (GoDaddy, Namecheap, Google Domains, Bluehost, DreamHost, etc). ◈ Websites/Web application development ✅ Fix errors related to websites/web applications built using HTML, CSS, JavaScript, PHP, and MySQL. ✅ Build web applications using the PHP Laravel framework. ✅ Development of backend APIs using Java Spring Boot framework. ✅ Third party API integrations. ◈ Infrastructure management in different Cloud Computing Platforms ✅ Amazon Web Services (AWS) ✅ DigitalOcean ✅ Google Cloud Platform (GCP) ✅ Microsoft Azure If you're looking for a dedicated and experienced developer/server admin who can deliver high-quality code and drive successful project outcomes, I'd love to chat with you. Let's work together to turn your vision into reality!

Enthusiastic, talented Senior Software Engineer with excellent programming skills, strong problem-solving abilities, quality-driven and customer-focused. Passionate not only about technology but also about applying it to improve people’s lives in new and innovative ways. Experienced in handling the entire software development life cycle, and used to working with a wide variety of technologies. A constant learner who motivates their peers. Self-motivated, positive, proactive and pragmatic, communicative and collaborative, and ready to take responsibility and ownership. EXPERTISE • Strong experience with Python, Go, Java, C, C++ and Lua; • Good Knowledge of Ruby and Js; • Solid experience with object-oriented design, and design patterns; • Experienced with UNIX operating system, including Linux for development and basic administration; • Familiarity with databases such as PostgreSQL, Oracle, MySQL and PL/SQL; • Experienced with OpenGL, 3D graphics, and ima​ging; • Great Computer Vision and OpenCV experience; • Good experience working with GUI development such as QT, Swing, and IUP; • Familiar with Web development: J2EE, Spring MVC, Tomcat, JSP, Servlets, JSF, HTML, CSS; • Good Knowledge with Multi-threaded and Client- Server programming; • Strong experience in design, unit testing, reviews, system testing, and requirements; • Experienced with all phases of product development lifecycle; • Experienced with source control systems like CVS, Subversion, JIRA, Buildbot and Hudson; • Familiar with agile methodologies as well as software planning and estimation techniques; • Strong commitment to life-long learning, enjoying teaching and mentoring; • Team oriented, encouraging the use of conventional procedures, practices, and tools; • Excellent written and verbal communication skills (English and Portuguese).

Hello! I’m a Full-Stack Software Engineer specializing in React (frontend) + Java (backend). I build scalable, maintainable, and performant web applications using PostgreSQL for databases and Docker for containerization and deployment. What I offer • Clean, responsive UI with React, modern JS/ES6+ standards, component-based architecture • Backend API development with Java (Spring Boot, etc.), RESTful services, business logic, authentication/authorization • Database design, query optimisation, using PostgreSQL • Deployment & dev‐ops support: Docker containers, Docker Compose, CI/CD pipelines • Good communication, clean code, test/unit/integration where possible Why work with me • I deliver on time, with good documentation • I’m proactive, suggest better solutions, care about maintainability • I like long-term projects & helping clients build solid foundations Looking for: freelance / contract work in full-stack, frontend React, backend Java, apps, microservices, etc. Let’s build something awesome together.

• Software Engineer with over 12 years of experience in designing, developing, and supporting enterprise-grade software systems. • Proficient in Java, Spring / Spring Boot / Spring AI / Quarkus / LangChain4J • Experienced with Groovy / Grails / Micronaut and C# / .NET • Hands-on experience building AI-powered applications and intelligent agents using Large Language Models (LLMs) integrated via LangChain4J and Spring AI • Build custom AI developer tooling — skills, plugins, and coding knowledge-base projects — that codify engineering best practices into reusable workflows • Practical experience using AI coding agents and assistants — Claude Code, Codex, and Grok — to accelerate development, refactoring, and code review workflows • Proven track record in enterprise application development and high-availability system support • Core expertise across Web, Desktop, and Cloud-based solutions • Strong ability to collaborate effectively in multicultural and distributed teams • Extensive hands-on experience in software research, design, development, testing, and deployment

Building Reliable Software That Actually Works I'm a software engineer who believes good code isn't just about making things work - it's about making them work well, consistently, and without surprises down the road. Over the past few years, I've specialized in building backend systems and microservices for enterprise applications. My sweet spot is creating APIs and services that handle real-world complexity while staying maintainable and scalable. My technical toolkit: Java • Kotlin • Python • Spring Framework • Docker • Kubernetes • CI/CD • Cloud Infrastructure

Transforming Ideas into Scalable Digital Solutions As a Full Stack Developer & Solution Architect, I specialize in designing and delivering high-performance, secure, and scalable web applications tailored to business needs. From concept to deployment, I focus on clean architecture, efficiency, and long-term maintainability. Core Expertise Backend Development Java, Spring Boot, Microservices Architecture, Hibernate Python for automation, integrations, and data processing REST APIs, system integrations, and performance optimization Database design & tuning (MySQL, PostgreSQL, MongoDB) Frontend Development Modern UI development with ReactJS & Angular Responsive design using HTML5, CSS3, Bootstrap Advanced UI libraries: PrimeReact, PrimeAngular, Ant Design AI & Intelligent Integrations Integration with Claude AI and modern LLMs for smart automation AI-powered features like chatbots, content generation, and workflow enhancement DevOps & Tools Docker, CI/CD pipelines, Git (GitHub, GitLab) Cloud-ready solutions with scalable deployment strategies What You Can Expect Clean, production-ready code Scalable and future-proof architecture Strong focus on performance, security, and reliability Clear communication and on-time delivery Let’s build powerful, intelligent, and scalable solutions that drive real business impact. 🚀

Why Choose Me as Your Development Partner? I’m a Senior Full-Stack & Mobile Developer (9+ years) who helps founders and teams turn ideas into production-ready web, mobile, and AI-powered products — fast, clean, and scalable. I combine strong engineering fundamentals with modern vibe-coding workflows to ship faster without cutting corners. ⸻ ✅ Proven Track Record • 🏆 Top 1% Rated Freelancer on Upwork • 🏆 1000+ hours of successful client delivery • 🏆 60+ projects delivered with consistent quality • 🏆 100% Job Success Rate • 🏆 Clean, maintainable, production-ready code ⸻ 🔧 Core Expertise (Full-Stack + Mobile) Frontend & Mobile • React, Next.js, Angular, Vue • React Native, Flutter, Ionic • TypeScript, JavaScript Backend • Node.js, Express • Java (Spring Boot) • Python, Go Databases & APIs • PostgreSQL, MongoDB • REST & GraphQL APIs • Elasticsearch • Vector databases (Pinecone, FAISS, Chroma) Cloud & DevOps • AWS (EC2, S3, Lambda) • Docker, Kubernetes • CI/CD (GitHub Actions, Jenkins) • Terraform (IaC) ⸻ 🤖 AI, RAG & Vibe Coding (Done Right) I build real AI systems, not demos. AI & RAG • OpenAI, Claude, Gemini integrations • End-to-end RAG pipelines (ingestion → embeddings → retrieval → re-ranking) • Secure data sources (PDFs, Docs, Notion, DBs, APIs) • AI chatbots for SaaS, internal tools, and customer support • Token cost & performance optimization Vibe Coding Workflow • Cursor, Windsurf, Claude Code • Replit & Replit Agent • Lovable.dev, Bolt.new • AI-assisted refactoring, testing, and reviews 👉 Human judgment + AI speed = reliable software ⸻ 🌟 How I Add Value I don’t just code — I: • Think like a product owner • Improve existing codebases without breaking things • Reduce tech debt and improve maintainability • Communicate clearly and proactively • Respect timelines, budgets, and existing architecture ⸻ 📩 Let’s Work Together If You Need ✔ Rapid MVPs or startup builds ✔ AI / RAG implementation ✔ Web or mobile app development ✔ Code cleanup, refactoring, or modernization ✔ A reliable long-term development partner 💬 I’m open to negotiation and long-term collaboration.

I specialize in full-stack development using the MERN stack (MongoDB, Express, React, Node.js) and Java Spring Boot. My focus is on building reliable backend systems and clean, responsive frontend interfaces. 🔹 Backend Development RESTful API design and development (Node.js / Express / Spring Boot) JWT-based authentication and role-based authorization systems Secure password handling and user authentication flows Database integration with MongoDB and relational databases Middleware implementation (logging, error handling, CORS configuration) 🔹 Frontend Development Responsive and interactive UI development using React State management using Context API API integration using Axios Authentication flows (login, registration, protected routes) 🔹 DevOps & Software Practices Basic CI/CD understanding and deployment workflows Git version control and collaborative development Docker fundamentals for containerized applications Agile development methodology and iterative delivery

Experienced Senior Web & Mobile Developer | Full-Stack Expertise | Scalable & Business-Driven Solutions With a strong background in full-stack development, I have built and deployed high-performance web and mobile applications for businesses across industries. My experience spans ERP systems, e-commerce platforms, tender management software, and real-time analytics solutions—all designed for scalability, security, and business growth. I have over 9 years of experience as a full-stack web developer, working across a wide range of technologies and platforms. Below is a detailed list of my expertise: Backend Technologies: - Java EE: Experienced in developing enterprise-level applications using Java EE. - Spring & Spring Boot: Proficient in building scalable, secure, and efficient backend applications using the Spring framework and Spring Boot. - Microservices: Expertise in designing and developing microservices-based architecture, ensuring modular and scalable solutions. - RESTful & SOAP Web Services: Skilled in designing and implementing both REST and SOAP-based web services for seamless communication between systems. Frontend Technologies: - JavaScript: Strong knowledge of JavaScript, enabling dynamic and interactive web applications. - DHTMLX: Experience with the DHTMLX JavaScript library to create responsive and interactive UIs. - AngularJS & Angular 13: Proficient in using AngularJS for legacy applications and Angular 13 for modern web applications, ensuring high performance and maintainability. - ReactJS: Experience in building fast, dynamic, and responsive user interfaces using ReactJS. - VueJS: Knowledge of VueJS for developing progressive web applications with a focus on simplicity and flexibility. Databases: - MySQL: Experienced in designing and managing relational databases using MySQL, optimizing queries for performance. - SQL Server: Proficient in SQL Server, including database design, performance tuning, and writing complex queries. - Oracle: Expertise in Oracle databases, including PL/SQL programming and database management. - PostgreSQL: Skilled in using PostgreSQL for high-performance, scalable database solutions. Cloud Technologies: - AWS: Extensive experience with various AWS services such as DynamoDB (NoSQL database), EC2 (virtual servers), S3 (storage), API Gateway (API management), AWS Lambda (serverless computing), and AWS Cognito (authentication). - GCP: Knowledge of Google Cloud Platform for cloud infrastructure, including computing, storage, and data management solutions. DevOps: - Jenkins: Experience with Jenkins for continuous integration and continuous delivery (CI/CD) pipelines, automating the build and deployment process. - Docker: Skilled in using Docker for containerization, ensuring consistent environments across development, testing, and production. - Kubernetes: Proficient in using Kubernetes for container orchestration, managing and scaling containerized applications efficiently. Reporting & Business Intelligence: - Jasper Reports: Expertise in using Jasper Reports for generating reports and integrating them into web applications. This comprehensive set of technologies has allowed me to build, deploy, and manage end-to-end solutions, ensuring high-quality results across various web development projects. 🔹 Why Work With Me? ✔ Real-World Business Impact: I develop customized solutions that directly improve business operations, efficiency, and revenue. ✔ End-to-end Project Execution: From requirement analysis to deployment, I handle everything. ✔ Reliable & Scalable Architecture: I build future-proof applications that scale with your business. ✔ Client-Focused Approach: Understanding your needs and delivering solutions tailored to your business model is my top priority. Let’s discuss how I can bring value to your next project! 📩 Message me now to get started!