Hire the Best Java Collections Framework (JCF) Professionals

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Daria N.

Ukrainka, Ukraine

$45/hr
5.0
2 jobs

๐Ÿ‘‹ Hello! Senior Java Developer, Team Lead & Architect with 10+ years of hands-on experience with 10+ years of hands-on experience building scalable, high-load web and mobile applications. I mainly work with Java backend, JavaScript, TypeScript, Oracle, Postgres databases. My core backend work is centered on Spring Boot, focusing on API development and production-grade RESTful services backed by PostgreSQL. My focus is on backend software architecture, ensuring scalability, clean boundaries, and long-term maintainability. โœ”๏ธ Ready-to-Use Integrations I can accelerate your product using proven, production-ready integrations: ๐Ÿš€ AI & LLMs: ChatGPT, LLaMA, Mistral (text, images, vision, automation) ๐Ÿš€ Payments: Stripe (card payments & transfers) ๐Ÿš€ Voice & Media: ElevenLabs (speech & voice AI) ๐Ÿš€ Communication: Zoom (voice & video integrations) My Specialization: โœ… Backend & Architecture: Java (10+ years): modern Java (Lambdas, Streams, Date/Time API), Spring (9+ years): Spring Boot, Spring Data, Spring Cloud for microservices and distributed systems, and Java EE: REST APIs, SOAP, JPA, third-party integrations โœ… Security & Frameworks: Keycloak with OAuth2 and JWT-based authentication, JHipster, Swagger, Liquibase, Axon, Vaadin, ORM: Hibernate, Blaze-Persistence โœ… Databases & Messaging: SQL (10+ years): PostgreSQL, MySQL, MariaDB, Oracle, NoSQL: MongoDB, Redis, Hazelcast, Messaging: Kafka, ActiveMQ, RabbitMQ, Zookeeper, Firebase Messaging โœ… DevOps & Observability: CI/CD: Jenkins, Docker, Kubernetes, ELK Stack (Logstash, Elasticsearch, Kibana) โœ… Quality & Delivery: Testing: JUnit, Mockito, Spring Test, Unit & Integration testing, Full SDLC, code reviews, refactoring, clean architecture ๐Ÿ’ก Letโ€™s discuss how I can help you build a reliable, scalable solution!

  • Java
  • Spring Boot
  • RESTful API
  • Apache Kafka
  • PostgreSQL
  • Spring Framework
  • Spring Cloud
  • Docker
  • Kubernetes
  • OAuth
  • Hibernate
  • CI/CD
  • API Development
  • Software Architecture
Shahbaz A.

Hyderabad, Pakistan

$45/hr
5.0
20 jobs

Full Stack Java Engineer with 5+ years of experience building scalable, production-grade systems for logistics, food delivery, and enterprise platforms. I specialize in Spring Boot microservices architecture and AI-powered backend systems โ€” designing end-to-end solutions that handle high traffic, complex workflows, and real-time data processing. My background in logistics technology means I understand not just the code, but the business operations behind it. What I bring to your project: - AI integration using OpenAI, Gemini, and LangChain4j for intelligent automation and chatbot backends - Microservices architecture with Spring Boot and Spring Cloud - Event-driven systems using Apache Kafka and RabbitMQ - Full stack development with React.js and Vue.js frontends - REST API design, development, and third-party integrations - AWS infrastructure โ€” EC2, RDS, S3, deployment pipelines - Database design and optimization across MySQL, PostgreSQL, and Oracle - JWT-based authentication and Spring Security - Legacy system migrations and monolith-to-microservices transitions - Docker, CI/CD pipelines, and production deployment I have built and maintained systems processing hundreds of thousands of records daily โ€” including a 2.5-year long-term engagement delivering a full-stack logistics and food delivery platform on AWS, earning a 5.0 rating across every review. I do not disappear after handing over code. I ask the right questions before starting, communicate clearly throughout, and flag issues before they become problems. Clients who work with me once tend to come back. 100% Job Success Score across every contract on Upwork. If you need a reliable full-stack engineer who builds intelligent, scalable systems โ€” let's talk.

  • Java
  • Spring Boot
  • REST API
  • Microservice
  • Apache Kafka
  • Amazon Web Services
  • Spring Security
  • API Integration
  • Spring Cloud
  • Hibernate
  • MySQL
  • PostgreSQL
  • MongoDB
  • Spring MVC
  • Next.js
  • Vue.js
  • RabbitMQ
  • React
  • Docker
  • Artificial Intelligence
Khawaja H.

Daska Kalan, Pakistan

$22/hr
5.0
19 jobs

A ๐“๐จ๐ฉ ๐‘๐š๐ญ๐ž๐ ๐Ÿ๐ฎ๐ฅ๐ฅ ๐ฌ๐ญ๐š๐œ๐ค ๐๐ž๐ฏ๐ž๐ฅ๐จ๐ฉ๐ž๐ซ ๐ฐ๐ข๐ญ๐ก ๐š ๐Ÿ๐ŸŽ๐ŸŽ% ๐‰๐จ๐› ๐’๐ฎ๐œ๐œ๐ž๐ฌ๐ฌ ๐’๐œ๐จ๐ซ๐ž building Java Spring Boot backends, modern web apps, n8n automations, and WordPress solutions that are robust, scalable, and delivered on time. I work at the intersection of enterprise backend engineering, full stack product development, AI-powered workflow automation, and WordPress helping startups launch MVPs quickly and helping businesses eliminate the manual work that slows their teams down. ๐Ÿš€ What I'm Best At: ๐Ÿ”น๐‰๐š๐ฏ๐š & ๐…๐ฎ๐ฅ๐ฅ ๐’๐ญ๐š๐œ๐ค ๐ƒ๐ž๐ฏ๐ž๐ฅ๐จ๐ฉ๐ฆ๐ž๐ง๐ญ (๐œ๐จ๐ซ๐ž ๐ž๐ฑ๐ฉ๐ž๐ซ๐ญ๐ข๐ฌ๐ž): โ˜• ๐‰๐š๐ฏ๐š ๐„๐œ๐จ๐ฌ๐ฒ๐ฌ๐ญ๐ž๐ฆ: Spring Boot, Spring MVC, Spring Security, Spring Data JPA, Spring Cloud, Hibernate, Kotlin ๐Ÿ–ฅ๏ธ ๐…๐ซ๐จ๐ง๐ญ๐ž๐ง๐: Next.js, React, TypeScript, Angular, Tailwind CSS ๐Ÿ’ป ๐๐š๐œ๐ค๐ž๐ง๐: Node.js (Express, NestJS), Python (FastAPI, Django) ๐Ÿ’พ ๐ƒ๐š๐ญ๐š๐›๐š๐ฌ๐ž๐ฌ: PostgreSQL, MySQL, MongoDB, Redis โ˜๏ธ๐ƒ๐ž๐ฏ๐Ž๐ฉ๐ฌ & ๐‚๐ฅ๐จ๐ฎ๐: AWS (EC2, S3, RDS, CloudFront, Lambda), Docker, Kubernetes, GitHub Actions, Jenkins ๐Ÿ”น n8n Automation & AI Workflows: ๐Ÿง  Workflow Automation: n8n, Zapier, Make connecting your tools and cutting out repetitive manual work entirely ๐Ÿค– AI Integration: OpenAI, Claude, Gemini embedded intelligently into your products and business processes ๐Ÿ“ฃ CRM & Lead Automation: email pipelines, WhatsApp, Slack, webhook-driven workflows, outreach systems ๐Ÿ“ฆ Custom Automations: data sync, onboarding flows, report generation, notification systems, document processing ๐Ÿ”น WordPress & WooCommerce: โšก Custom themes and plugins built from scratch no bloated templates ๐Ÿ›’ WooCommerce: payments, subscriptions, multi-vendor marketplaces ๐Ÿ” Performance optimization, security hardening, malware cleanup, and full site migrations ๐Ÿงฉ Page builders: Elementor Pro, Divi, Bricks, WPBakery, Gutenberg ๐Ÿ”น Why Work With Me: โ€บ Top Rated with 100% Job Success consistent results across every engagement โ€บ I take full ownership of outcomes not just tasks and keep you informed at every step โ€บ Clean, well-documented code your team can maintain without needing me forever โ€บ AI-powered development workflow: I ship faster without sacrificing quality or cutting corners โ€บ Clear, proactive communication you'll never be left guessing about progress โญ What clients say: "Hamdan demonstrated strong expertise in Java Spring Boot and Next.js clean, efficient code that met all requirements." Marketplace Platform (681 hrs ยท $2,241) "Completed the AWS deployment exactly as promised. Highly recommend for CI/CD and AWS configuration." Spring Boot + AWS DevOps "Very understanding and always available. He makes sure everything is clear before moving forward." n8n CRM Automation "Delivered exactly what was needed with minimal instructions. Sincere, hard-working โ€” I would highly recommend." NestJS / Angular + DevOps ๐Ÿค Let's Talk โ€” you might be a great fit if you need: - A Java Spring Boot API or full stack web application built properly from day one - An n8n automation workflow that saves your team hours every single week - A marketplace, SaaS MVP, or internal tool launched in weeks not months - A fast, secure, and conversion-ready WordPress or WooCommerce site - A reliable developer who communicates clearly, delivers consistently, and cares about your success Click "Invite to Job" or send me a message I'd love to hear about your project. ๐Ÿš€

  • Java
  • Spring Boot
  • API
  • RESTful API
  • Docker
  • React
  • Amazon Web Services
  • API Integration
  • MySQL
  • Spring Security
  • Spring MVC
  • Spring Framework
  • Spring Batch
  • Microservice
  • J2EE
Kashaf S.

Lahore, Pakistan

$5/hr
5.0
6 jobs

๐Ÿ‘‹ Hello, I'm Kashaf Shanawar! Iโ€™m a passionate Java & Angular Developer with expertise in building dynamic, scalable, and high-performing web applications. With over 2 years of hands-on experience, I specialize in designing and developing full-stack applications with robust Java Spring Boot backends and interactive Angular frontends. ๐Ÿ’ก What I Offer: โœ… Full-Stack Development โ€“ Expertise in Java Spring Boot and Angular, ensuring seamless integration between backend and frontend. โœ… API Development & Integration โ€“ Proficient in creating and securing RESTful APIs. โœ… Database Management โ€“ Experienced with MySQL, PostgreSQL, and MongoDB for efficient data storage and retrieval. โœ… Authentication & Security โ€“ Implementing Spring Security & JWT for secure applications. โœ… Microservices Architecture โ€“ Developing scalable and distributed systems with Spring Boot microservices. โœ… Trading Systems Development โ€“ Worked on real-time trading platforms integrated with stock exchanges, handling market data, FIX protocols, and order management systems (OMS). ๐Ÿ›  Tech Stack: Backend: ๐Ÿ”ฅ Java (JDK 8, 11, 17, 21) | Spring Boot | Spring Security | Hibernate (JPA) | REST APIs | Microservices | Kafka Frontend: โšก Angular | TypeScript | JavaScript | HTML5 | CSS3 Database: ๐Ÿ“Œ MySQL | PostgreSQL | MongoDB Tools & Platforms: ๐Ÿš€ Git | Jira | Postman | Docker ๐Ÿ’ผ Work Experience: ๐Ÿ”น Java Angular Developer | Softech Systems Limited (2023 โ€“ Present) Building scalable Java Spring Boot applications with REST APIs & microservices. Developing real-time trading platforms with Pakistan Stock Exchange (PSX) & Ghana Stock Exchange integration. Enhancing Order Management System (OMS) and implementing STOP/LOSS trading functionalities. Revamping the trading terminal using Angular for a smoother user experience. ๐Ÿ”น Full Stack Java Angular Intern | Zin Technologies (2023) Developed full-stack applications with Java Spring Boot, Angular, and MySQL. Worked in Agile environments with Git and Jira for project management. ๐Ÿ”ฅ Why Hire Me? โœ” 100% Client Satisfaction โ€“ I prioritize delivering high-quality, well-structured, and efficient code. โœ” Deadline-Oriented โ€“ I ensure timely delivery while maintaining excellent code quality. โœ” Strong Problem-Solving Skills โ€“ I love challenges and always find innovative solutions. โœ” Effective Communication โ€“ Clear, proactive, and transparent communication for seamless project execution. โœ” Continuous Learner โ€“ Always eager to explore the latest technologies and best practices. ๐Ÿ“ฉ Letโ€™s Work Together! Looking for a reliable, detail-oriented, and skilled full-stack developer to take your project to the next level? Let's discuss how I can help! ๐Ÿ“จ Message me now, and let's build something amazing together! ๐Ÿš€

  • Java
  • Web Application
  • CSS
  • HTML
  • Spring Boot
  • Microservice
  • Angular
  • MySQL
  • Spring Security
  • Spring Framework
  • Kafa
  • Websockets
  • Hibernate
  • JavaScript
  • TypeScript
John R.

Cairo, Egypt

$25/hr
4.8
15 jobs

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).

  • Java
  • Spring Boot
  • Spring Framework
  • RESTful Architecture
  • REST API
  • Microservice
  • Amazon Web Services
  • Kotlin
  • MySQL
  • PostgreSQL
  • Git
  • Apache Kafka
  • Scrum
  • Apache Maven
  • Docker
Ashok K.

Jaipur, India

$25/hr
4.9
46 jobs

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

  • Java
  • Spring Boot
  • RESTful API
  • SQL
  • Spring Batch
  • Spring Security
  • Docker
  • Documentum
  • Elasticsearch
  • Apache Kafka
  • Amazon ECS for Kubernetes
  • Microservice
  • Hibernate
  • Websockets
  • Swing

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