With 10+ years building Java backend systems, I deliver production-ready software end-to-end — from API design and domain logic to the pipeline and environment it runs on. Most senior Java engineers hand off deployment to someone else. I don't. When there's no DevOps engineer on the team, I cover that ground myself — setting up CI/CD pipelines, containerizing services, configuring cloud environments, and making sure what I build actually runs reliably in production. You get one engineer who takes full ownership of delivery, not a gap between dev and ops that someone else has to fill. I also integrate AI-assisted development tools into my workflow to move faster and keep costs down for clients. I work with my preferred toolset by default, but if your team has privacy or data security requirements, I'm happy to work within your approved tools or constraints — no friction. Clients typically come to me with: ✅Backend systems that need to be built right from the start — clean design, solid APIs, room to scale ✅Legacy Java codebases that need modernizing without breaking what works ✅Microservices that need to be decomposed, redesigned, or made deployable ✅Teams without a dedicated DevOps engineer who still need a proper delivery setup I work across the full backend lifecycle: design, build, containerize, automate, ship, and monitor. ➤ Backend Engineering ✅Spring Boot & Spring Cloud microservices ✅REST & GraphQL API design ✅Event-driven systems (RabbitMQ and similar) ✅Database design & optimization (SQL & NoSQL) ✅System design for scalability and maintainability ➤ Delivery & DevOps — when the team needs it ✅CI/CD pipelines (GitHub Actions, GitLab CI, Jenkins) ✅Docker & Kubernetes — containerization and orchestration ✅Infrastructure as Code (Terraform) ✅AWS & Azure — environments that support your full SDLC ✅Monitoring & observability (Prometheus, Grafana, ELK) ➤ What I Deliver ✅Well-structured backend systems your team can extend without pain ✅APIs designed for clarity, consistency, and long-term maintainability ✅Deployable, containerized services — not "works on my machine" software ✅Automated pipelines and stable environments when there's no DevOps engineer to own them ✅Production setups that are observable, cost-aware, and right-sized for your stage ✅Faster delivery and lower effort costs through AI-assisted development — with full respect for your data privacy preferences ➤ Working Style ✅I take full ownership — design decisions, delivery, and outcomes ✅Honest scope estimates, no surprises mid-project ✅I document what I build, so your team isn't dependent on me ✅Strong async collaboration across US, EU, and other time zones ➤ Industries ✅SaaS platforms & product companies ✅Startups and scale-ups ✅Enterprise engineering teams If you need a senior Java engineer who won't stop at writing code — someone who can take a feature from design to production without handing off to a specialist — let's talk. Message me and I'll review your current setup or requirements and tell you honestly what I can deliver and how. 🔑 Keywords Java, Spring Boot, Spring Cloud, Microservices, REST API, gRPC, RabbitMQ, Backend Developer, API Design, System Design, AWS, Azure, Kubernetes, Docker, Helm, Terraform, CI/CD, Bitbucket, Jenkins, Infrastructure as Code, Monitoring, Prometheus, Grafana, ELK Stack, Observability, Database Design, MySQL, MongoDB, SaaS Backend, Cloud Automation, SDLC, AI-Assisted Development, Productivity, Senior Java Developer

Java software engineer with 7+ years of experience. I have a deep understanding of core Java components (such as multithreading, persistence, concurrency etc), advanced knowledge of Object Oriented Programming concepts and Object-Oriented Design principles. Adept at learning new skills rapidly. Skills • Java SE and J2EE; • Object Oriented Programming concepts; • Design Patterns(Singleton, Factory Method, Abstract Factory, Strategy, Iterator ...) • Spring, Spring Boot, JPA, Hibernate; • Experience in designing a MySQL and Postgres databases; • NoSQL, GraphQL • AWS, Azure, Jenkins • Maven, Gradle • Version controls: Git; • HTML, CSS, LESS; • JavaScript; • Bootstrap, JQuery, Node.js, EJS; • AJAX; Languages English – Upper intermediate; Work history Feb 2022 – Present Java Backend developer 9bits • Implemented backend services in a rental agency that ensure a sound and scalable system. • Designed and implemented various database solutions, enhancing data consistency and query performance. • Streamlined deployment pipelines using Bitbucket, improving CI/CD automation and development workflow. Technologies: Java - Spring Boot - REST - MySQL - Azure - Docker - Bitbucket Nov 2020 – Feb 2022 Java Backend developer Urgently • Developed the backend for a roadside assistance service, ensuring high availability and reliability • Microservices-based architecture put into place to raise the modularity and scalability of the system • Created automated CI/CD pipelines via Jenkins and Bamboo Technologies: Java - Spring Boot - Microservices - MySQL - GraphQL - Flyway - Jenkins - AWS Aug 2019 – Sep 2020 Software developer Workmovr • Delivered and maintained multiple commercial projects (websites for hospitals, shipping applications etc) • Integrated external APIs and ensured smooth data flow between services • Configured and managed deployment pipelines with Docker and AWS Technologies: Java - Spring Boot - Node.js - PostgreSQL - MongoDB - AWS Feb 2018 – Jul 2019 Java Backend Developer Iqualif • Tasked with the developing system for parsing White and Yellow Pages, Instagram poster, etc • Designed the architecture of the entire application Technologies: Java - Spring - REST - MySQL Personal qualities • Purposefulness; • Persistence; • Sociability;

I’m a Top-Rated (5⭐️) Full Stack Engineer with over 4+ years of experience delivering high-quality backend systems, APIs, and full-stack web applications. I specialize in Java/Kotlin with Spring Boot on the backend and Vue/Nuxt on the frontend, supported by modern DevOps and cloud-native practices. I help teams build reliable, scalable, and maintainable software systems, whether it's creating new applications from scratch or improving and refactoring existing codebases for better performance and maintainability. 🔧 My Expertise Covers 🔹 Building RESTful APIs and microservices using Spring Boot (Java/Kotlin) 🔹 Real-time web applications using WebSocket (e.g., chat, live updates) 🔹 Implementing secure authentication & SSO with OAuth 2.0 and OpenID Connect 🔹 Full-stack development with Vue.js, Nuxt.js, Tailwind CSS, and Bootstrap 🔹 Working with relational (PostgreSQL, MySQL), in-memory (Redis), and graph (Neo4j) databases 🔹 Automating CI/CD workflows using GitHub Actions and Docker 🔹 Provisioning and deploying to GCP services (Cloud Run, Cloud SQL, GCS, Cloud Tasks, Cloud Scheduler, Load Balancer) 🔹 Deploying and managing applications on Linux VPS (Ubuntu) 🚀 What I Bring 🔹 Clean, modular, and well-documented codebases 🔹 End-to-end ownership from architecture to deployment 🔹 Real-time, scalable solutions tailored to your product needs 🔹 Proactive communication and on-time delivery 🔹 Strategic insight to improve features, reliability, and scalability Whether you need a full-stack developer to take your product from idea to launch, or a backend specialist to build real-time APIs and services, I’m ready to contribute to your success. Let’s build something exceptional.

Are you seeking a proficient developer with 4 years of experience in AI/ML, Python, Java, and C++? I am proficient in: ✅Developing AI/ML Algorithms ✅ Fine-Tuning LLMs (ML, DL models) ✅Building Rag Applications ✅Python Scripting & Automation ✅Desktop Application Development ✅C++ Programming ✅Algorithm Development and Optimization I specialize in Developing Advanced RAG applications, writing optimized ML algorithms. I finetune large language models on your own dataset. Transformer, BERT, GPT, whatever architecture you want, I'll handle it. I do full fine-tuning, LoRA, and QLoRA depending on what fits your hardware and the model size. You don't have to worry about the technical side I set up everything, run the training, and give you the final model ready to use. What I Do ✅ Clean, fix, and prepare your dataset ✅ Format everything the right way (COCO-style if needed, or whatever your model expects) ✅ Run fine-tuning with proper configs ✅ Give you evaluation results so you actually know the model improved Deliver the final model + instructions so you can run it yourself What You Get ✅Fully fine-tuned model ✅Training logs ✅Evaluation metrics ✅Dataset formatting (if you don't have one, I'll build it) ✅Support until everything works on your side Models I Can Fine-Tune ✅LLaMA ✅Mistral ✅Qwen ✅GPT-style models ✅Classification models (BERT, RoBERTa, DeBERTa, etc.) ✅Vision-Language models Anything that can be fine-tuned, I can handle it Who This Is For ✅Startups ✅Researchers ✅Solo developers ✅Anyone who needs a model trained on their own data Extra If you don't have training data, I can help you create, clean, or structure it so it My other expertise lies in developing automation using Python and creating Python scripts to perform different tasks, and also in desktop application development using Java, leveraging my skills to create efficient and user-friendly software solutions. Throughout my career, I've focused on developing desktop applications that meet client needs and exceed expectations. With a strong foundation in Java, Python, and C++ for various programming tasks My approach emphasizes clean, scalable code and a commitment to delivering projects on time and within budget. Whether it's enhancing existing applications or developing new software solutions, I am committed to providing high-quality results that align with your business objectives. If you don't like my work, you don't have to pay a penny! i believe in delivering quality work rather than charging my clients for nothing Let's discuss how I can contribute to your projects and help you achieve success through innovative software solutions. I look forward to collaborating with you!

I build payment systems and the AI agents that run on top of them. I am a senior backend engineer with 9+ years in Java and Spring Boot, including 4+ years on the billing and payments platform behind a marketplace moving about $4B a year. PAYMENTS AND FINTECH I deliver provider integrations end to end: Adyen, Braintree, Payoneer, PayPal, Venmo, Wise, Wells Fargo, Bank of America and Forter, on a platform operating across 180+ countries. My work covers card processing, wallets, payouts, bank transfers, fraud screening and reconciliation over REST, SFTP and webhooks. I have also integrated Stripe, FastSpring and bank vPOS in client products. Representative work: - Migrated a major payout provider from a legacy protocol to REST with OAuth 2.0. The migration covered payouts, mass payouts, payee registration, card release and reconciliation. I shipped it to 100% behind feature flags with no customer-facing incidents. I built provider emulators to test it without vendor sandboxes. - Designed a card-processing service on a provider's GraphQL API covering client tokens, payment methods, network tokens, cryptograms, authorization, capture, refunds, cancellations and 3D Secure. - Built a forwarding layer that routes network tokens between two providers, enabling non-US card acceptance. I rolled it out in stages and negotiated timeout SLAs directly with the vendor. - Authored the design for splitting a payments monolith into nine provider-specific microservices. Domain coverage: 3DS2, network tokenization, cryptograms, authorization and capture, refunds, chargebacks, reconciliation through APIs, webhooks and SFTP files, idempotency and double-charge prevention, mass payouts, ACH returns, fraud screening, PCI-aware design. AI AGENTS AND LLM SYSTEMS I build AI that runs inside products with real users and revenue. I built an agentic system that investigates failed payment transactions on its own, reasoning across logs, dashboards, source code and incident tooling to cut manual triage. I built it with Python, LangChain and multi-agent orchestration. It runs in a high-stakes payments environment, where being wrong has a cost. I also built and run Memabooks, a profitable AI commerce product that turns a child's photo into a personalized illustrated storybook. The books are printed on demand and shipped worldwide, with customers in eight countries. I developed a multi-stage, identity-preserving image generation pipeline covering face detection, background removal, personalized character generation, skin-tone matching and character consistency across a complete book. I work with diffusion models, fine-tuned LoRA adapters and serverless GPU inference, tuning for quality, latency and cost. I also built the Node/NestJS backend, the Angular front end, print-on-demand fulfilment, and the payment stack for a market with limited access to major global processors: bank vPOS, 3DS2, Apple Pay, idempotency and double-charge prevention, and abandoned-payment recovery. AI stack: LangChain, LangGraph, LlamaIndex, multi-agent systems, RAG and multimodal RAG, vector databases (FAISS, Chroma), Model Context Protocol, OpenAI, Gemini, Azure AI. BACKEND ENGINEERING AND RANGE My core stack is Java 17 and Spring Boot. I also have production experience with Node.js, NestJS, TypeScript, Python, PostgreSQL, MongoDB, AWS, Docker, Kubernetes, REST, GraphQL, microservices and event-driven architecture. I was the sole engineer responsible for Geoapify's product surface for 17 months, working directly with the product owner across 14 repositories. I built a geocoding SaaS end to end, covering file upload, worker-based job processing, object storage and card payments. I maintained their public TypeScript SDKs for MapLibre GL, Leaflet and GeoJSON, which see about 55K npm downloads a month, and owned their public API playgrounds and OpenAPI specs. Testing is part of my delivery process. On one project, I built 260 Playwright end-to-end tests from scratch in about six days. WHAT I CAN HELP WITH - Payment provider and fintech integrations - Java and Spring Boot backend development - Backend architecture and monolith-to-microservices migrations - AI agents, RAG and LLM integration - API design, reliability, observability and production troubleshooting CREDENTIALS - Oracle Certified Professional: Java SE 11 Developer - IBM RAG and Agentic AI Professional Certificate - Google Cloud Generative AI Leader - Microsoft Azure AI Fundamentals - BSc in Computer Science, American University of Armenia - Former Java lecturer, Russian-Armenian University My longest engagement here ran 19 months and 2,700+ hours. I am open to long-term, full-time and contract-to-hire engagements. Tell me what you need built or what is currently breaking. I will tell you honestly whether I am the right engineer for it.

Senior Java Backend Developer with 10+ years building production systems using Spring Boot, REST APIs, and enterprise databases. CORE EXPERTISE: - Spring Boot, Spring MVC, Spring Data JPA, Spring Security - RESTful API design and development - Database design: MySQL, Oracle - Enterprise system integration - Production support and troubleshooting WHAT I DELIVER: - Spring Boot Enterprise applications and RESTful APIs - Database design and optimization (PostgreSQL, MySQL, Oracle) - System integrations and workflow engines - Application support and troubleshooting RECENT HIGHLIGHTS: - Built configurable workflow engine processing thousands of events - Designed multi-system integrations with comprehensive error handling - Kotlin + Spring Boot experience TECHNICAL SKILLS: Java, Spring Boot, Spring Framework, Kotlin, REST APIs, PostgreSQL, MySQL, AWS, Docker, Git, Agile/Scrum MICROSERVICES KNOWLEDGE: - Strong understanding of microservices architecture patterns through coursework and demo projects. Seeking opportunities to apply this knowledge in production environments and build distributed systems expertise under experienced architects. I have a 5.0 Upwork rating and clients describe me as "professional, responsive, and genuinely committed to delivering high-quality work." Available for long-term contracts (30+ hours/week).

🚀 Solutions Architect & Technical Lead with 8+ years of hands-on experience in enterprise backend engineering, cloud architectures, and modern full-stack development. As the technical lead behind the UISS agency, I focus on crafting resilient, high-performance, and secure software solutions tailored for FinTech, Healthcare, and scalable business products. 💡 MY CORE SPECIALTIES: • Enterprise Backend: Java (Spring Boot, Spring WebFlux, Hibernate, Spring Data) • Frontend Excellence: Angular (TypeScript, Angular Material) • High-Speed Mobile & MVP: FlutterFlow / Cross-platform app development • Data & Architecture: PostgreSQL, Docker, Microservices, and RESTful API design • Intelligent Features: AI Development & LLM Integration (OpenAI API, Custom Agents) 🛠️ ENGINEERING HIGHLIGHTS & APPROACH: • Legacy Modernization: Extensive experience in complex enterprise system upgrades (e.g., migrating Core Java and Spring Boot ecosystems to the latest LTS versions), significantly improving execution speed, dependency management, and security compliance. • Robust Integrations & Security: Expert in designing secure API layers, implementing centralized authentication/authorization models (OAuth2/OIDC, Keycloak), and orchestrating microservices networks. • Scalability & Clean Code: Strong advocate for domain-driven design, test-driven development (TDD), and transparent Agile/Scrum delivery that bridges the gap between technical complexity and business goals. Whether you need to untangle legacy monolithic code, optimize high-load databases, build an AI-driven automation layer, or launch a production-ready mobile MVP via FlutterFlow—I bring the architectural oversight and execution power to make it happen. 📩 Let’s transform your requirements into a stable, future-ready product. Reach out, and let’s connect!

I'm a Full Stack Developer and Java Developer with 5+ years building backend systems, software platforms, SaaS applications, web applications, and enterprise systems for clients across fintech, logistics, telecommunications, retail, healthcare, and SaaS. As a full stack developer and Java developer, I design, build, and ship production-ready software systems and platforms end-to-end architecture, backend, frontend, and deployment. On the backend, my core stack is Java, Core Java, Spring Boot, and Spring Framework, building REST APIs, microservices, and scalable software systems with Hibernate/JPA, SQL, PostgreSQL, MySQL, and MongoDB. As a Java backend developer, I've designed 120+ REST APIs and built 10+ microservice architectures for systems and platforms serving 10K to 500K+ users. I've shipped 35+ production software systems, platforms, and web applications as a full stack developer and Java developer. On the frontend, I build with React, Angular, JavaScript, and TypeScript, delivering full stack web applications and SaaS platforms where clean UI meets solid backend architecture. Whether it's a software system, an internal platform, or a customer-facing SaaS product, I work across the whole stack to make sure the system holds up in production. For infrastructure, I work with AWS, GCP, and Azure, using Docker, Kubernetes, and CI/CD pipelines to keep systems, platforms, and software reliable at scale. The software systems and platforms I've maintained as a full stack developer and Java developer have held 99.9% uptime — the result of solid monitoring, careful deployment practices, and proactive system design. Performance is something I take seriously on every platform and system I build: I've cut API response times by up to 60% and improved overall system performance by 40%+ through targeted software architecture improvements rather than costly rewrites. I've also worked extensively with enterprise-level database schemas, optimizing complex SQL queries and data models across tables with 100K+ records. Beyond Java, I also write Python, PHP, and Node.js when a software system or platform calls for it, and I've worked on .NET/C# projects too, including reviving a legacy .NET system onto currently supported frameworks. As a full stack developer, I go where the project needs me. Java is my strongest ground, but I adapt the stack to the system. Beyond hands-on development, I've led teams, mentored junior developers, and managed cross-functional projects across software systems and SaaS platforms. My clients get clear communication, fast responses, and maintainable software code that still makes sense six months later. I'm open to long-term collaborations on full stack development, Java, Spring Boot, backend systems, SaaS platforms, software systems, web applications, and microservices. If you need a full stack developer or Java developer who ships reliable software and platforms, let's talk.

I'm a Principal Software Engineer with over 10 years of experience building backend applications using Java and Spring Boot. Most of my work has been on enterprise products where reliability, scalability, and clean architecture matter more than simply getting features delivered. I've designed and developed microservices, REST APIs, authentication systems, and event-driven applications for industries including retail, logistics, construction, identity management, and enterprise SaaS. I enjoy working on complex backend problems, whether it's designing a new service, improving an existing system, or troubleshooting production issues. My core expertise includes: • Java (8, 11, 17, 21) • Spring Boot, Spring Security, Spring Data JPA • Microservices Architecture • REST APIs and third-party integrations • PostgreSQL, MongoDB, MySQL, Redis • Kafka and asynchronous messaging • Docker, Kubernetes • AWS (EC2, S3, RDS, IAM) • Keycloak and OAuth2/JWT authentication • GitHub Actions, GitLab CI/CD • Performance optimization and production support Over the years I've worked on systems serving thousands of users where stability, security, and maintainability were critical. My approach is to understand the business problem first and then build solutions that are easy to maintain and scale. I also have extensive experience reviewing code, mentoring developers, improving application performance, and resolving production issues. Whether it's optimizing database queries, reducing API response times, refactoring legacy code, or designing a new microservice, I focus on delivering solutions that work well in production. If you're looking for someone who can contribute beyond writing code, communicate clearly, and take ownership of backend development from design through deployment, I'd be happy to discuss your project.

Java sits at the center of the platforms I build. Spring Boot runs the backend services and APIs, handling business logic, data access, and the core behavior of the system. Many of these platforms pair a Spring Boot backend with Angular on the frontend, forming structured web applications such as internal dashboards, operational platforms, and SaaS systems used by teams every day. Angular provides the application interface while the Java backend manages services, data, and integrations behind the scenes. Python also comes into play when automation or data workflows are needed. Small services and scripts written in Python handle background tasks, integrations, and operational processes that support the main platform. Java and Spring Boot handle the backend services, Angular runs the platform interface, and Python supports automation and background tasks.