Hire the Best JUnit Specialists in Yerevan, AM

I am a skilled Java Backend Developer with strong experience designing and building scalable, high-performance backend systems. Throughout my career, I’ve developed expertise in Java and a wide range of modern backend technologies and frameworks. ✅My core skills include: ✔️Java (19+), Spring Framework, Spring Boot, Spring Data JPA, Spring Security, Spring AOP ✔️RESTful APIs, GraphQL, Web Services ✔️Hibernate, Microservices Architecture ✔️Databases: MySQL, PostgreSQL, Oracle ✔️Build & DevOps Tools: Maven, Docker, Git ✔️Event Streaming: Apache Kafka I earned a certification as an AI Automation Specialist (n8n), expanding my skill set in automation and intelligent system development. I also have working knowledge of additional technologies such as C++, Python, and frontend basics, giving me a well-rounded understanding of full-stack development. I'm passionate about clean code, efficient systems, and delivering reliable, production-ready solutions. Whether you're building a new backend service or need help improving an existing one, I'm here to help.

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. Over 10,000 books created so far, 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.

Java & Spring Boot specialist — 7+ years building backend systems that hold up in production: fintech, risk/compliance, and SaaS platforms with real users. Most projects stall for the same reason: the backend needs one person, the frontend another, the cloud a third, and none of them talk to each other. I take the whole delivery instead — architecture through to deployment. What clients hire me for: → Backend systems — Java/Spring Boot microservices, REST and GraphQL APIs, Kafka event pipelines, secure authentication. I've built enterprise compliance platforms covering 50+ organizational workflows. → Cloud & DevOps — AWS and GCP architecture, Docker, Kubernetes, CI/CD pipelines. Serverless setups with CDK/Lambda/Cognito that scale under load and cost pennies at low traffic. → Frontend & mobile, when the project needs it — React, Next.js, React Native/Expo. I built a cross-platform fintech product (web, desktop, mobile) from a single TypeScript monorepo. I also work with: Micronaut, Kotlin, Node.js, PostgreSQL, MySQL, MongoDB, DynamoDB, gRPC, WebSockets. My longest engagement here ran 15 months and 563 hours with one client. I'm built for long projects and ongoing ownership, not one-off tasks. Clear communication, delivery on time, and a timezone that overlaps Europe (CET+2). Whether you're a CTO or a non-technical founder, I'll explain the trade-offs in plain language. What are you building? Let's talk.

Six years of Java backend work — the last three on a cybersecurity risk and compliance (GRC) platform, in a team where every developer owned a project end to end: gathering the requirements, writing the technical documentation, then building and delivering it. One engagement there ran 23 consecutive months with no break in the contract — 3,890 hours. Alongside that I work as a third-line support engineer at Sembi, on PreEmptive and Kiuwan, its two software-security products, and on Xblend/Xray. Third line is the last tier before an issue goes unresolved, and it changed how I build: I debug my own systems under real load, so fixes hold instead of coming back. What I work with: → Backend — Java, Spring Boot, Spring Security, OAuth 2.0, Keycloak, Spring MVC and WebFlux, JPA/Hibernate, REST, GraphQL → Messaging & infrastructure — Apache Kafka, AWS (Aurora, EKS, RDS, S3, Cognito, IAM, SNS, SQS, SES), Docker, Kubernetes, Jenkins, CircleCI → Data — MySQL, PostgreSQL, MongoDB including Reactive Mongo, DynamoDB → Production ownership — Grafana, log streams, incident diagnosis, post-incident review Security work shaped my defaults. When the product itself is about risk controls and audit evidence, access control, traceability and data retention stop being things you bolt on later. I am probably a good fit if you need someone to take over an existing Spring Boot service, to replace a backend developer who is leaving, or to build something where security is a requirement rather than a checkbox. MSc in Computer Software Engineering and BSc in Applied Mathematics, Yerevan State University. AWS re:Invent grantee 2023. English certified here on Upwork. My hours overlap Europe (UTC+4) and I reply within a few hours.

As a Senior Java/AI Engineer with over 12 years of experience, I specialize in building scalable, secure, and high-performance systems using Java, Spring Boot, and Spring Security. My background spans across microservices, event-driven, and service-oriented architectures, enabling me to deliver robust, maintainable backend solutions. I have deep expertise in Kafka, RabbitMQ, and RESTful API design, combined with hands-on experience integrating AI-driven and data-centric technologies like LangChain, LangFlow, Qdrant, and OpenAI APIs — bridging traditional backend systems with modern LLM-powered workflows. I’m passionate about system design, clean architecture, and test-driven development, and thrive in Agile teams where collaboration and innovation are key. My focus is on crafting elegant, future-ready solutions that accelerate business value and enhance user experience. Driven by curiosity and continuous learning, I’m always exploring emerging technologies in AI, distributed computing, and knowledge retrieval, and applying them to create intelligent, scalable Java ecosystems.