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Hi, I’m Dejan Keserović, a Senior Full-Stack Software Developer with 5+ years of experience building scalable, high-performing web applications. I’ve worked on a wide range of projects, from high-scale enterprise systems to personal side projects, helping businesses improve their software and streamline processes. I handle both frontend and backend development and take pride in managing projects from start to finish, ensuring smooth and efficient execution. I also have a strong background in database design, with research experience that’s given me a deep understanding of how to structure and optimize databases for large and complex systems. I’ve published several scientific papers on the topic and was also a speaker at the International Conference on Information Systems Development (ISD) 2025. My key skills and technologies include: • Java, Java/JEE, Spring Boot, Spring Framework (MVC, Security, Data) • Maven, Gradle • .NET, C# • React, TypeScript, HTML, CSS • SQL databases: MySQL, MSSQL, Oracle, PostgreSQL • REST API development and integration • Writing clean, efficient, and well-tested code • Project design, testing, deployment, and maintenance • Strong communication and collaboration I’m looking forward to working together!

Are you looking for a developer who can build modern, intelligent, and scalable web applications powered by AI automation? 👋𝙄 𝙖𝙢 𝙎𝙮𝙚𝙙 𝙍𝙖𝙯𝙖 𝙃𝙖𝙞𝙙𝙚𝙧, a passionate Full-Stack Developer and AI Engineer with a strong background in building AI-integrated web apps, chatbots, automation systems, and backend infrastructures that help businesses scale faster and work smarter. 𝗪𝗵𝗮𝘁 𝗜 𝗢𝗳𝗳𝗲𝗿 🧠 AI Integration & Automation ▪ Build Agentic AI systems using CrewAI, LangGraph, LangChain, and Autogen ▪ Create RAG pipelines with Pinecone, Weaviate, PGVector, or FAISS ▪ Design AI-powered assistants, chatbots, and knowledge-base bots ▪ Develop automated workflows using N8N, Python, Playwright, or Puppeteer ▪ Integrate LLM models (GPT-4, Claude, Gemini) into live systems 𝗙𝘂𝗹𝗹-𝗦𝘁𝗮𝗰𝗸 𝗪𝗲𝗯 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 (MERN & Next.js) ▪ Build responsive, dynamic web apps using MongoDB, Express, React, and Node.js ▪ Next.js with server-side rendering & SEO optimization ▪ Secure RESTful APIs / GraphQL integrations ▪ Authentication, role-based access, and real-time functionality 𝗦𝘆𝘀𝘁𝗲𝗺 & 𝗜𝗻𝗳𝗿𝗮𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲 𝗘𝘅𝗽𝗲𝗿𝘁𝗶𝘀𝗲 ▪ Dockerized deployments, Linux VPS, Azure, and AWS setup ▪ Virtualization: VMware, vCenter, vMotion, vSAN ▪ CI/CD pipelines using Azure DevOps ▪ Monitoring and performance optimization with Grafana, Kibana, Nagios 𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗘𝘅𝗰𝗲𝗹𝗹𝗲𝗻𝗰𝗲 ▪ Beautiful, modern UI with TailwindCSS, Material UI, and Framer Motion ▪ Pixel-perfect, mobile-friendly interfaces that load fast and convert better 🌟 Why Clients Hire Me ✅ All-in-One Expertise - From backend to AI integration, I handle the entire lifecycle. ✅ Result-Focused Development - I build solutions that actually solve business challenges. ✅ Clean Code & Scalability - My systems are modular, secure, and built to grow. ✅ Clear Communication - Regular updates, transparency, and collaborative workflow. ✅ Proven Projects ▪ Agentic AI System (CrewAI + LangGraph) ▪ N8N Automation for E-commerce Order Management ▪ Chatbot with RAG Pipeline (LangChain + Pinecone) ⚡ 𝗟𝗲𝘁'𝘀 𝗕𝘂𝗶𝗹𝗱 𝗦𝗼𝗺𝗲𝘁𝗵𝗶𝗻𝗴 𝗜𝗻𝘁𝗲𝗹𝗹𝗶𝗴𝗲𝗻𝘁 𝗧𝗼𝗴𝗲𝘁𝗵𝗲𝗿 If you want your next-generation AI system or web application built with precision, scalability, and intelligence, let's connect. 👉 𝐒𝐞𝐧𝐝 𝐦𝐞 𝐚 𝐦𝐞𝐬𝐬𝐚𝐠𝐞, 𝗮𝗻𝗱 𝗹𝗲𝘁’𝘀 𝗯𝗿𝗶𝗻𝗴 𝘆𝗼𝘂𝗿 𝗶𝗱𝗲𝗮 𝘁𝗼 𝗹𝗶𝗳𝗲.

I'm a senior software engineer with 10+ years building scalable backend systems, data infrastructure, and CI/CD pipelines for fintech, medtech, e-commerce, and SaaS companies. I specialize in transforming legacy applications into modern, cloud-native architectures and delivering production-ready solutions. WHAT I DO BEST Backend Development: PHP (Laravel, Symfony, Zend, PHP 8+, WordPress), Python (FastAPI, Flask), Node.js (NestJS, Express.js), RESTful APIs, microservices, event-driven systems, database optimization (MySQL, PostgreSQL, Redis, DynamoDB) Data Engineering: ETL/ELT pipelines with DBT, Snowflake, Apache Spark (Scala), data modeling and SQL optimization, real-time processing, workflow orchestration (Airflow, Dagster) DevOps and Cloud: AWS (Lambda, EC2, ECS, RDS, S3, SQS/SNS), Infrastructure as Code (Terraform, Ansible), containerization (Docker, Kubernetes), CI/CD (GitHub Actions, GitLab CI/CD, Jenkins, Bazel), monitoring (CloudWatch, Prometheus, Grafana) Database Engineering: MySQL and PostgreSQL (performance tuning, indexing, replication), NoSQL (DynamoDB, Redis), search engines (Solr, Elasticsearch), data warehousing (Snowflake) SERVICES I OFFER Backend API Development: Build secure, scalable REST APIs and microservices from scratch or enhance existing systems Legacy System Modernization: Refactor monolithic applications into maintainable, cloud-ready architectures DevOps and Infrastructure Automation: Set up CI/CD pipelines, containerize applications, automate deployments with Terraform Data Pipeline Engineering: Design and implement ETL/ELT workflows for analytics, reporting, and data integration Cloud Migration and Optimization: Migrate on-premise systems to AWS with cost optimization and scalability Technical Consulting: Architecture reviews, performance audits, and technical roadmap planning WHAT SETS ME APART Production-Ready Code: Every delivery includes clean, documented code, comprehensive testing, and deployment automation Full Lifecycle Ownership: From architecture design to production deployment and post-launch support DevOps Mindset: I build systems that are easy to deploy, monitor, and maintain Clear Communication: Regular updates, transparent timelines, and collaborative problem-solving Long-Term Thinking: Solutions built for maintainability, not quick fixes that create technical debt IDEAL PROJECTS Building backend APIs and microservices. Data pipeline development and warehouse integration. AWS infrastructure setup and optimization. CI/CD pipeline implementation. Legacy application modernization. Database design and optimization. Kubernetes deployment and orchestration. RECENT WORK Architected enterprise-grade CI/CD pipelines using GitHub Actions and Bazel, reducing deployment time by 40%. Built comprehensive data pipelines using DBT and Snowflake for fintech client. Refactored legacy e-commerce backend to Laravel, improving performance by 50%. Designed AWS infrastructure using Terraform for scalable cloud deployments. MY APPROACH I believe great engineering isn't just about writing code, it's about building systems that empower teams to move faster and ship with confidence. Whether you need a one-time API service or complete platform overhaul, I focus on delivering solutions that are robust, scalable, and easy for your team to evolve. Available for short-term projects and ongoing collaborations. If you're looking for a senior engineer who can architect, build, and deploy backend systems or data infrastructure with a DevOps-first mindset, let's discuss your project.

Senior Backend developer, building Python and Go services for SaaS, healthcare, and AI infrastructure at a Top Rated Plus Upwork agency. 7+ years of senior Backend engineering across Go and Python. Currently Senior Backend Engineer at HTEC, building Go microservices for AT&T's AI chatbot service. Prior: Team Lead on a FHIR-compliant Backend telemedicine platform at Proactive Health Tech (10+ Go services, healthcare data architecture, Python data pipelines). Native English, Bosnian, Croatian. Through Interactivated Solutions, a Top Rated Plus Upwork agency: 38,916 hours, 310+ contracts, 100% Job Success, 200+ public reviews. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ⭐⭐⭐⭐⭐"We brought Mesha in as our Backend lead to take over a stalled microservices rebuild. He took the Go services off the previous team's hands, rewrote three of the worst-performing endpoints, and tightened the Python data pipeline that was choking under load. Calm, honest about what wouldn't work, fast on what would. The kind of Backend engineer who actually ships." - Marko T., CTO ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Most Backend engineers come up through one language and learn the next when forced to. I came up through Go and systems engineering, then layered Python for data pipelines, ML infrastructure, and the cases where Python's ecosystem is the right tool. Senior Backend work where the language choice serves the problem, not the resume. Native English on every standup, every Loom, every Backend code review. Recent Backend work spans enterprise and product builds. At HTEC, senior contributor on AT&T's AI chatbot service - Go Backend microservices, inference routing, and downstream system integration. Prior: Team Lead at Proactive Health Tech, 10+ Go services handling patient records, scheduling, video session orchestration, and HL7/FHIR integration, plus Python pipelines for analytics and reporting. Through Interactivated Solutions, 310+ shipped contracts across SaaS, healthcare, fintech, and AI infrastructure. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ WHAT I DO ▸ Backend services and microservices - Go (Gin, Fiber, Echo) or Python (FastAPI, Django), REST and gRPC, PostgreSQL data layer. ▸ Backend APIs at production scale - rate-limiting, idempotency, retries, structured logging, observability that survives a 3am incident. ▸ Backend rescues - inheriting a stalled Go or Python codebase, stabilizing services, getting the team back to shippable. ▸ Backend for AI infrastructure - inference routing, model serving, embedding pipelines, vector DB integration, Python data pipelines feeding production ML. ▸ Backend data engineering - Python ETL pipelines, Pandas / Polars, async workers, batch and stream processing, Go for high-throughput hot paths. ▸ Backend team leadership - I lead Backend teams of 3-5 engineers, code-review heavy, CI gates that catch the drift juniors miss. ▸ Backend performance work - query tuning, service profiling, infrastructure right-sizing, real load testing on real data. ▸ Full stack developer and software developer foundations - front end experience with React and Node.js, web developer capabilities for full-cycle delivery. ▸ Adjacent stack: Docker, Kubernetes, Terraform, AWS, GCP, Redis, Kafka, PostgreSQL, OpenAI and Anthropic API integration. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ HOW I WORK Every Backend engagement starts with a discovery pass on the existing codebase before a line of code changes. Service boundaries, data flow, and observability gaps mapped upfront. Async with daily updates, Claude Code and AI tooling to move faster without compromising stability. Documented handoff so the Backend is maintainable after the engagement ends. MY PROCESS ▸ Day 1-3: Backend discovery on the Go or Python codebase, identifying load-bearing trade-offs. ▸ Week 1: stable Backend services, branch hygiene, CI gates, observability baseline. ▸ Weeks 2-4: Backend feature shipping in two-week iterations. Code review before merge. ▸ Continuous: working code in your repo end of day. You own the Backend codebase and every architecture decision is yours to question. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Already have a project in mind? Send me a message - no brief needed. I will help map out the scope and see what is possible before committing to anything.

Senior DevOps & Site Reliability Engineer with 7+ years building resilient, scalable infrastructure for software and AI/ML workloads. I specialize in: - CI/CD pipeline design and automation (Jenkins, GitHub Actions, GitLab CI) - Kubernetes orchestration and containerized deployments (Docker, EKS, OpenShift) - Cloud infrastructure on AWS, GCP, and Azure - AI/ML infrastructure: GPU provisioning, model serving pipelines, MLOps tooling - SRE practices: monitoring with Prometheus/Grafana, incident response, SLO/SLI management - Infrastructure as Code (Terraform, Ansible, CloudFormation) With $100K+ earned and 100% Job Success on Upwork, I help teams ship faster, reduce downtime, and build the infrastructure foundation that AI-driven products need. Whether you're deploying ML models to production or scaling your platform, I'll automate and harden the path from code to customer.

With a rich background spanning over 5 years in the realm of Web Development, I have honed my expertise across a spectrum of technologies. 🟢 On the backend, I command the Python stack with proficiency in Django, FastAPI, Flask, and Falcon. 🟢 On the frontend, I navigate the diverse landscape of the Javascript stack, encompassing React, Vue, and Next. Beyond these core technologies, my enthusiasm extends to versatile platforms like WordPress, and I find joy in harnessing the power of Docker. My commitment to staying abreast of modern technologies ensures that I approach each project with a dynamic and comprehensive skill set, ready to craft innovative solutions at the intersection of backend and frontend development. What sets me apart is my resourcefulness in programming, enabling me to navigate diverse challenges with ease. I have a proven track record of creating scripts to integrate enterprise asset management systems with other systems, facilitating seamless communication and data exchange. Let's collaborate to bring your projects to life. Contact me, and let's build something exceptional together.