Hire the Best Java Developers

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.

STRIPE CONNECT | STRIPE BILLING | STRIPE RADAR | STRIPE API | STRIPE CHECKOUT | STRIPE TERMINAL | FINTECH | SAAS | AI | PAYMENTS | COMPLIANCE (PCI DSS, GDPR) If Stripe is slowing down your product, breaking your billing logic, or causing failed payments you can’t explain, I can fix that. I’ve delivered 100+ Stripe integrations for SaaS and tech companies, and I’m a 4× Stripe Certified professional. You’re not getting a basic integration, you’re getting a payments system designed to reduce churn, recover revenue, and scale with your growth. I specialize in building Stripe systems that directly impact metrics like churn, AOV (Average Order Value), LTV, and checkout conversion rates. I don’t just plug APIs. I step into your architecture and make sure your billing, subscriptions, and payment flows are optimized end-to-end. I can help if you’re dealing with: 🔹 High checkout abandonment rates 🔹 Unexpected churn from failed payments or poor retry logic 🔹 Broken or confusing subscription upgrades/downgrades 🔹 Low AOV due to poor pricing or payment flow design 🔹 Inconsistent or unreliable webhook handling 🔹 Stripe setups that “work” but don’t scale What I can help you with: 🔹 End-to-end Stripe integration for SaaS platforms 🔹 Subscription architecture (plans, trials, proration, lifecycle logic) 🔹 Reducing churn with smarter retry logic and dunning strategies 🔹 Checkout optimization to improve conversion rates 🔹 Webhook architecture (reliable, scalable, no missed events) 🔹 Stripe account audits with revenue-focused insights 🔹 Advanced Stripe products (Connect, Sigma, custom workflows) If you already have developers, I can work directly with them or guide them through the correct architecture in live sessions. Most Stripe implementations leave money on the table. I help you close those gaps so your payments system actually drives revenue, not just processes it. If you want to improve conversion, reduce churn, or fix hidden issues in your Stripe setup, send me a message and let’s take a look.

⭐⭐⭐⭐⭐ Top Rated Plus on Upwork 100% Job Success Score I'm a Java developer with 8+ years delivering production-grade systems from serverless AWS architectures to distributed microservices serving healthcare and fintech clients. 𝗪𝗵𝗮𝘁 𝗜'𝘃𝗲 𝗕𝘂𝗶𝗹𝘁 ➡ As lead Java developer at my current company, managed a team of 8 engineers over 7 years — delivering 4 production systems across healthcare, fintech, and AI verticals. ➡ Designed serverless AWS infrastructure for a US longevity and healthcare platform as an AWS developer — Lambda, AppSync, DynamoDB, Cognito, SNS/SQS, Stripe, HubSpot currently in production. ➡ Led migration from monolithic Spring apps to distributed microservices — reducing deployment complexity and enabling independent scaling per service. ➡ Built a PDF/UA accessibility compliance platform as backend developer using Java 21, iText 7, PDFBox, veraPDF processing and remediating documents of hundreds of pages against international accessibility standards. ➡ Delivered an AI-powered workflow automation platform as an AI developer integrating Spring AI, Azure cloud, and automated Stripe subscription workflows. ➡ Shipped a medical practitioner dashboard integrating 3rd-party hardware APIs and clinical toolkits as backend developer and tech lead serving real patients and practitioners in production. Core experience as a Java developer and Backend developer As a Java developer with 8+ years in production systems, my core is Java 8 through Java 21 with the full Spring ecosystem Boot, Cloud, Security, WebFlux, Batch, and Spring AI for AI-integrated backends. I work across both relational (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB, Redis) databases, selecting the right store based on access patterns not habit. As a backend developer I've optimised slow MongoDB queries to cut response times, redesigned DynamoDB access patterns for a high-throughput healthcare API, and built Redis caching layers that kept latency flat under load. As an AWS developer, my hands-on stack covers Lambda, AppSync, DynamoDB, Cognito, SQS, SNS, SES, S3, API Gateway, Route 53, and CloudFormation built and maintained in a live US healthcare platform. I design serverless pipelines end-to-end, not just deploy to them. For async workloads I wire event-driven systems using Kafka, RabbitMQ, or AWS SNS/SQS depending on durability and throughput requirements. On the container side: Docker, Kubernetes, Helm, OpenShift, Terraform, and Jenkins full IaC from infrastructure definition to CI/CD pipeline. As an AI developer, I've shipped Spring AI integrations for workflow automation backends, built document intelligence services capable of processing and remediating hundreds-of-pages PDFs against accessibility standards, and connected GraphQL APIs via AWS AppSync for mobile and web AI-driven applications. I also have production experience integrating medical hardware APIs, Stripe subscription billing, and HubSpot CRM sync into Java backends the kind of third-party integration work every backend developer eventually owns in a real product. AWS Developer & 𝗖𝗹𝗼𝘂𝗱 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝗶𝗻𝗴 ✅ Currently operating as AWS developer on a live healthcare platform Lambda, AppSync, DynamoDB, Cognito, SQS/SNS/SES, S3, API Gateway, Route 53, CloudFormation ✅ Experience as AWS developer across serverless, containerized (ECS/K8s), and IaC (Terraform, CloudFormation) environments ✅ Also experienced across Azure (AKS, Azure DevOps) and GCP as multi-cloud backend developer ✅ Kubernetes, Helm, Docker, OpenShift, Jenkins, Terraform the full DevOps chain every AWS developer deploys through AI developer 𝗖𝗮𝗽𝗮𝗯𝗶𝗹𝗶𝘁𝗶𝗲𝘀 ✅ Delivered AI-powered backend services as AI developer using Spring AI automated content generation and workflow orchestration at scale ✅ AWS AppSync + DynamoDB + Cognito pipeline for a live healthcare platform: the architecture an AI developer builds when latency and data integrity are non-negotiable ✅ Experienced AI developer integrating third-party AI tooling with enterprise Java backends designing event-driven pipelines that handle async AI workloads via Kafka and SQS ✅ As AI developer, built document intelligence features automated PDF tagging, structure remediation, and accessibility validation across large document corpora 𝗜𝗻𝗱𝘂𝘀𝘁𝗿𝗶𝗲𝘀 Healthcare · Fintech · SaaS · E-commerce · Logistics · Telecom · IoT · Blockchain · Automotive · Media 𝗦𝗽𝗲𝗰𝗶𝗮𝗹𝗶𝘇𝗮𝘁𝗶𝗼𝗻𝘀 & 𝗥𝗼𝗹𝗲𝘀 ✔ Senior Java Developer · Java Spring Boot Developer · Java Backend Developer ✔ AWS Cloud Engineer · AWS DevOps Engineer ✔ Azure Cloud Engineer · Google Cloud Engineer ✔ AI Backend Developer · Full-Stack Developer (Spring Boot + React) ✔ AI Backend Developer · Full-Stack Developer (Spring Boot + React) Need a Java developer, backend developer, AWS developer, or AI developer who ships production systems — not prototypes? Drop me a message. 04/06/2026

🟢 AVAILABLE TODAY, JUNE 23 ⚡ 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.

I'm Huanqing Zhu, and you can call me Fusion. With over 10 years of hands-on Java development experience—including 6 years dedicated to big data processing and visualization—I’ve built my expertise by staying rooted in frontline coding, even as my responsibilities have grown. A key pillar of my technical toolkit is ‌6 years of production-grade Rust development experience‌, complemented by proficiency in Java, Scala, JavaScript, HTML5, and a full stack of big data and cloud-native technologies: Apache Spark, Hadoop, Hive, Flume, HBase, Storm, Kafka, DataX, ECharts, Docker, Kubernetes, and Linux. What sets me apart is that I’ve never stepped away from writing production code, even as I’ve taken on leadership and architectural roles: As a ‌hands-on Big Data Developer‌, I’ve built robust data ingestion utilities (including the open-source DataXServer on GitHub) and real-time page click analytics systems, directly coding pipelines to pull data from RDBMS, NoSQL databases, and file storage into production environments. As a ‌Big Data Architect‌, I’ve led platform design while still contributing core code, using Hadoop, Spark, Flink, and ElasticSearch to build scalable data infrastructure—no abstract planning here; I’ve written the critical components that power these systems. As a ‌Rust Specialist‌, my 6 years of experience spans building high-performance, low-latency systems. I’ve used Rust to optimize data processing pipelines, cut latency by up to 40% in high-throughput scenarios, and deliver systems that run 24/7 with zero critical errors. As a ‌Team Leader‌, I’ve managed full-stack teams (Java, front-end, QA, operations) while still pairing with developers on complex code reviews and contributing to high-priority features, ensuring I stay connected to the day-to-day challenges of software delivery. I also bring deep experience in microservices architecture and cloud-native containerization, and my cross-language expertise lets me bridge gaps between Java-based enterprise systems and Rust-powered high-performance components. If you’re looking for a professional who combines strategic vision with the grit to deliver production-ready code—someone who can architect a system, and write the Rust or Java code that makes it run—I’m the candidate for you. Thank you for reviewing my profile. I’m eager to discuss how my hands-on experience can add value to your team.