I started programming as a kid and it’s been more than 20 years now. My first language was Pascal, then C/C++ and then I moved on to interpreted languages, like PHP or Python. My professional career in web programming began back in 2011: since then I have delivered dozens of web applications in PHP (Symfony, Laravel) and Python (Django), among others. I treat my experience as a responsibility: I know what works and what doesn’t and I can judge the consequences of many technological choices - that’s why I am always honest and realistic with my clients, offer my advice, and if necessary, try to dissuade them from solutions that might not work as they have envisioned. My main focus is on code quality and practicality. My ambition is to write reliable, fast, easy-to-modify code that can be written in a relatively short time. I always seek a balance between perfection and practicality in my coding (since the road to perfection is infinite and time until the deadline is not). I am a strong proponent of code that can be documented only by its contents and unit tests. I am also a fast learner. I don’t treat any framework as anything more than another tool made for convenience. When the need arises, I can learn most programming libraries and frameworks on the spot (as long as it's in a programming language I know). I always enjoy a new challenge! My technical expertise covers: - Databases: PostgreSQL, MySQL, SQLite, Oracle, MongoDB - VCS: Git, SVN, Mercurial - Issue trackers: Jira, Asana, Redmine, Trello, Harvest - Hosting: AWS, Linode, CPANEL/WHM, GoDaddy, Github Pages - Server OSes and tools: GNU/Linux (experience with most of popular distributions), Kubernetes (minikube, EKS), AWS Lambda, Apache2, Nginx (php-fpm and uwsgi), Ansible - Code quality: PHPUnit, Python unittest (also in conjunction with Django), pytest - Search: ElasticSearch, Solr - REST API development: experience in Django (REST Framework), FastAPI, Symfony, Laravel, and Node.js - 3D graphics programming: OpenGL in JS WebGL, C/C++ OpenGL libraries and PyOpenGL+pygame in Python - Others: Websockets (experience with implementation in Django, FastApi, Python in Lambda, Laravel and Ratchet). - Payment gateway integration: Paypal, Stripe, Braintree, Przelewy24 My technology stack: Backend: - PHP: Laravel, Symfony - Python: Django, FastApi - JS: Node.js Frontend: HTML, JavaScript, TypeScript, React, Angular.io and Angular.js, Vue.js, jQuery, Three.js, CSS, SASS, LESS, Tailwind, Bootstrap, AdminLTE Mobile technologies: React Native If you are looking for a reliable business partner, I have good news for you: I work with Polcode Software House - one of the top rated agencies on Upwork, located in Poland (EU). We have achieved an impressive 98% Job Success rate (with over 700,000 hours logged!). We are a team of about 150 people (developers, account managers, project managers, and graphic designers) whose daily job is problem-solving. We never leave a customer with an unfinished project: working in a team we can guarantee the project's continuity, no matter what happens. We are here to help you have your work done and finished. Please visit Polcode's portfolio and check our feedback! Looking forward to our cooperation! Best regards, Maciej Zakrzewski Senior Full Stack Python Developer Polcode Dev Team

Senior Java Fullstack Developer with 6+ years of experience building scalable, cloud-native enterprise systems using Spring Boot, React, Angular, Microservices, and AWS. I specialize in: - Java/Spring Boot backend development & REST API design - Microservices architecture with Docker & Kubernetes - Cloud deployment on AWS (EC2, S3, Lambda, RDS) - Frontend development using React, Redux, Angular, TypeScript - Database optimization (PostgreSQL, MySQL, MsSQL, Oracle, Sybase, MongoDB, Apache Solr, Redis, Elasticsearch, DynamoDB) - Event-driven systems with Apache Kafka & RabbitMQ - CI/CD pipelines with Jenkins, Maven & Git Projects I've delivered include real-time analytics platforms, fintech payment systems, e-commerce backends, and enterprise SaaS applications — all built for high availability and performance at scale. Top Rated Plus on Upwork (Top 3%) | 100% Job Success | Toptal Qualified (Top 3% Global Talent) If you need a reliable Java developer to architect and deliver production-ready backend systems, let's connect.

Most RAG applications never go beyond an MVP or a prototype. There's a reason for that: they are not architected or built with production-grade capabilities in mind. As a result, these MVPs: • Produce inaccurate results, such as hallucinations and biases • Are insecure, vulnerable to DDoS attacks, prompt injection, cascading failures, and other risks • Are highly expensive in terms of token usage If your next goal is to build a MVP, build it with production capabilities in mind from the start. The transition from MVP to full production will then be low-friction and straightforward. If you're ready to build a production-ready application right away, make sure it includes all the necessary capabilities to avoid unnecessary money spent and wasted effort. I am a software engineer with more than 10 years of experience developing production-grade data pipelines, search applications, and RAG systems. I have successfully delivered numerous RAG and Agentic RAG projects with true production-grade capabilities . What I Provide: Production-grade architecture and rapid development of RAG applications, including Agentic RAG systems, that are able to: • Accurately parse, chunk and ingest millions of documents • Handle thousands of requests per second • Remain highly secure against DDoS attacks, prompt injection, and other threats • Feature highly efficient data ingestion pipelines (e.g., accurately parsing thousands of PDF files, including tables spread across multiple pages and unknown layouts) • Deliver highly accurate RAG and Agentic RAG performance through data-driven error analysis AI evaluators and systematic improvement of prompt engineering, retrieval (like vector search), and LLM capabilities. If you want to start building serious, production-grade RAG applications instead of toy prototypes, contact me for a free assessment of your idea's viability and technical feasibility.

Need a production-ready AI system that actually works? I build LLM-powered, multi-agent solutions on GCP using LangChain and LangGraph — turning complex business workflows into reliable, scalable automation your team can ship. What sets me apart is the rare combination of deep backend engineering (9 years across Amazon, Groupon, and high-growth startups) and hands-on AI product building. I'm not just integrating APIs — I designed and shipped InterviewLM, an AI-native hiring platform, and Juliet, an agentic coding assistant. I understand how AI systems fail in production and how to build them so they don't. I specialize in: 🤖 Multi-agent orchestration with LangChain and LangGraph ☁️ GCP-native AI infrastructure (Vertex AI, Cloud Run, BigQuery) 🔍 RAG pipelines, vector search, and semantic retrieval ⚙️ Backend systems in Python, TypeScript, and Go that scale under real load 🔒 Fraud detection, data pipelines, and performance-critical APIs Here's what I can build for you: 🧠 Custom multi-agent AI systems that automate complex, multi-step business processes 📄 RAG-based document intelligence tools (contracts, support, knowledge bases) 🏗️ AI backend architecture — from prototype to production on GCP or AWS 🔗 LLM integrations with your existing stack (REST APIs, databases, internal tools) 📊 Data pipelines and analytics infrastructure using Spark, Redshift, or BigQuery Whether you need a proof-of-concept in days or a production system built to last, I scope clearly and deliver without surprises. ✅ Founder of InterviewLM — AI-native technical hiring platform used to evaluate engineers at scale ✅ Built agentic coding assistant Juliet, enabling developers to ship faster with AI-driven workflows ✅ Former SDE at Amazon and Groupon — shipped backend systems handling millions of transactions ✅ Led fraud prevention infrastructure at Pillow, reducing fraudulent activity across the platform ✅ 9 years of backend and distributed systems experience across fintech, logistics, and SaaS If you're building something with AI and need an engineer who has done it in production — not just in demos — send me a message. I typically respond within a few hours and happy to jump on a quick call to scope your project.

Over 14 years of Software experience in design, development and support of enterprise applications using enterprise Java technologies like ,SAP Commerce – Hybris , Solr/Elastic Search, Enterprise Search ,Spring , Hibernate, Struts, Java , J2EE , JDBC, JNDI, Internationalization (I18n) , Localization (L10n) , Liferay and relational databases such as Oracle, MySql.  Experience in providing 20+ Java / J2EE / Spring / Hibernate / UI Technologies / Build Technologies like Jenkins , Maven , SVN / Java script / jQuery / Angular.js /Backbone.js / Ext.js /Solr/ Elastic Search / Liferay Trainings / DevOps for International and Domestic clients5 Years of working experience with Sun Microsystem. 💡Sr Java Developer - Backend Developer 💡 Design and build micro-services using Spring boot. 💡Develop enterprise-grade highly scalable java based application. 💡Design and develop screens with JQuery, Javascript HTML5, CSS3, and Bootstrap. 💡Create JUnit test cases for Java-based applications. 💡Work with Quality Assurance for an end to end testing and certification of the product delivered. 💡 Work in a fast-paced environment that fosters growth and learning. 💡 Experienced in using frameworks such as Java/J2ee, Spring, Spring Boot 💡 Experienced in using build tools and source code repository tools such as: GiT, GitHub, Pull Request reviews, Gitflow branching strategies, and Maven 💡 Well experienced in developing and executing functional and integration tests 💡 Experience in developing and designing high performance, scalable and available web services (predominantly REST architecture) using J2EE and concurrency frameworks such as JAVA Concurrency package 💡 Experienced in the usage of NoSQL and NoSQL related tools applications, i.e. (near) real-time analytics 💡 Knowledge of object-oriented design and design patterns, and programming skills 💡 Experience in designing, developing and delivering software and/or platforms used by other developers, 💡 Good understanding of web services and SOA related standards like REST/OAuth/JSON and SOAP/WSDL. 💡 Devops

7+ Years of Experience | Top Rated Plus Most businesses don't struggle because of a lack of ideas—they struggle because their systems can't keep up. Slow development cycles, brittle architectures, disconnected tools, and the inability to utilize AI effectively often result in lost opportunities, operational inefficiencies, and increased costs. I help businesses build scalable backend systems and AI-powered applications that are designed for long-term growth. Over the past 7+ years, I have worked with startups, SaaS companies, agencies, and enterprise teams to design, develop, and maintain production-grade applications using Python and Django. As AI adoption accelerated, I expanded my expertise into Generative AI and LLM-powered systems, helping companies integrate intelligent capabilities into existing products and build AI-native applications from the ground up. I bring a unique combination of strong software engineering fundamentals and deep understanding of modern AI technologies. I can help you with: ================= • Building robust SaaS applications using Django and Django REST Framework • Designing scalable APIs using FastAPI and modern backend architectures • Developing secure, maintainable, and high-performance Python applications • Architecting multi-tenant SaaS platforms and enterprise systems • Database design, optimization, and performance tuning • Authentication, authorization, RBAC, JWT, OAuth, and SSO implementations • Background processing using Celery, Redis, and asynchronous task execution • Third-party integrations including payment gateways, CRMs, ERPs, and external services • Cloud deployment, CI/CD pipelines, monitoring, and infrastructure automation In addition to backend engineering, I specialize in integrating AI capabilities into real-world products. My AI expertise includes: ===================== • Building LLM-powered applications using OpenAI, Claude, Gemini, Llama, DeepSeek, Mistral, and Hugging Face • Designing Retrieval-Augmented Generation (RAG) systems with vector databases and semantic search • Developing AI copilots and domain-specific assistants • Building multi-agent systems using LangGraph, CrewAI, OpenAI Agents SDK, AutoGen, and PydanticAI • Implementing tool calling, structured outputs, and agent orchestration workflows • Developing document intelligence solutions involving OCR, extraction, classification, and validation • Creating conversational AI solutions for customer support, internal operations, and workflow automation • Integrating AI into existing SaaS platforms without disrupting current business processes Technology Stack =========== Backend & APIs Python, Django, Django REST Framework, FastAPI, Flask, Node.js AI & LLMs OpenAI, Claude, Gemini, Llama, DeepSeek, Mistral, Hugging Face, LangChain, LangGraph, CrewAI, OpenAI Agents SDK, AutoGen, PydanticAI, MCP RAG & Vector Databases Pinecone, Qdrant, Weaviate, Chroma, pgvector, Embeddings, Hybrid Search, Reranking Databases & Messaging PostgreSQL, MySQL, MongoDB, Redis, RabbitMQ Cloud & DevOps AWS, Docker, Kubernetes, GitHub Actions, CI/CD, Monitoring, Observability I focus on building solutions that are secure, scalable, maintainable, and production-ready. Whether it's a high-performance Django backend, an AI-powered SaaS platform, or an intelligent system powered by LLMs, my priority is delivering technology that creates measurable business value rather than experimental prototypes. If you're looking for an engineer who combines deep Python expertise with practical experience shipping AI systems into production, I'd be happy to help bring your vision to life.

Experienced Software and Data Engineer with over 13 years of experience building data-driven applications, RESTFul APIs, and microservices. I am familiar with the complete software development life cycle, build automation, infrastructure as code, and CI/CD development. Expertise: ======== -Programming Languages: Python, Java, Javascript, Go, Groovy, and SQL. -Data Stores: Postgres, DynamoDB, MongoDB, Redis, SQL Server, Oracle, Elasticsearch -Data Pipeline Orchestration: Nextflow, Spark, Airflow, Step Functions, Flink -DevOps: GitHub actions, Circle CI -Infrastructure as Code: Terraform, AWS CDK -Cloud Platforms: AWS -AWS: Familiar with building serverless systems and orchestrating with current IaC software development methodologies using CDK, Cloudformation Templates, and Terraform. -Other: Docker

Enterprise Architect | Fintech Infrastructure | Cloud & API Systems I’m a General Manager – Enterprise Architecture with 11+ years of experience designing and delivering large-scale technology platforms for banks, fintech companies, and enterprise organizations. My work focuses on building secure, scalable, and high-availability systems that support mission-critical financial services and high-traffic digital platforms. I have been involved in designing and implementing enterprise systems supporting national payment infrastructure and financial ecosystems used by multiple institutions and millions of users. Over the years I have worked on digital banking platforms, payment gateways, reconciliation platforms, API ecosystems, and cloud-native infrastructure. Core Expertise: • Enterprise Architecture & Technology Strategy • Fintech Platforms & Digital Payment Systems • Cloud Architecture (AWS, Kubernetes, Microservices) • API Architecture & Enterprise Integrations • Core Banking & Financial System Integration • High-Availability System Design • DevOps & CI/CD Automation • Security Architecture & Compliance Selected Achievements: • Designed payment infrastructure supporting 40+ financial institutions • Built scalable fintech platforms processing high-volume transactions • Led architecture modernization initiatives for enterprise financial systems • Delivered cloud-native architectures improving performance and scalability Clients typically engage me when they need a senior technology leader who can translate complex business requirements into scalable and reliable architecture. If you are building a fintech platform, scaling an enterprise system, or modernizing legacy infrastructure, I can help design the right architecture and implementation approach

🔸 Ex-CTO(5 Years) 🔸40+ Happy Clients 🔸1600+ high-quality hours 🔹India Based Full Time Freelance Cloud Technology Professional 🔹9+ Years of Professional Experience at Antino, Goldenflitch & ThinkDiffusion 🔹5+ Years of CTO Experience Leading Technology 🔹AWS - 8+ years experience 🔹GCP - 6+ years experience 🔹Azure - 6+ years experience 🔹DevOps and Terraform Expert 🔹Infrastructure as Code (IaC) Specialist 🔹Cost Optimisation Expert Full time freelance technology professional based on the Delhi, India. Expert in AWS and GCP, IAC, Containers & CICD. Regularly implements CI/CD pipelines using the most popular current toolsets including Jenkins, Github Actions, AWS CodeDeploy, etc. Automated infrastructure provisioning and post provisioning automation using Terraform and Ansible (to AWS, Microsoft Azure and GCP). Enterprise cloud migrations from on premise to cloud (AWS and Azure) and from cloud to cloud (AWS to Azure). Cloud infrastructure (Azure and AWS) analysis, optimization, consolidation and cost savings expert. 🔸Key Skills: Docker, Kubernetes, Terraform, ELK, CloudFront, ECS, NodeJs, Pyhton, AWS Services. Words from clients -------------------------------------------------------------------------------------------------------- "Ashish is very knowledgeable and has a keen technical understanding of AWS, GCP, Terraform, Ansible, Docker, kubernetes, DevOps, and Jenkins. He is a true DevOps expert and it's a pleasure working with him, I will definitely work with him on new opportunities in the future." (HSBC UK) "Ashish is a really experienced and very motivated person who helped us to set up our complete system on AWS. We were very happy with the results and we can recommend working with him!" (Hyderabad Metro Rail)

Hi, I'm Oleksiy. I am a senior engineer with 9 years of experience. I like to write clean code, and although I have a lot of experience, I spend time every day learning new languages, frameworks, optimizing workflows, and so on. One of my biggest strengths is solving problems. My task is to realize YOUR ideas and create an amazing product. I specialize in architecting high-scale e-commerce ecosystems and complex microservices. With a focus on the TALL stack and AWS, I transform business requirements into scalable, production-ready web applications. Technical expertise: Core Frameworks: ✔️ PHP 8.x, Certified Laravel Expert; ✔️ TALL Stack (Tailwind, Alpine, Livewire); ✔️ Filament PHP (Admin & Panels). AI & Intelligent Systems: ✔️ LLM Integration (OpenAI, Claude, OpenRouter); ✔️ Vector Databases; ✔️ AI-driven automation. Cloud Architecture (AWS & GCP): ✔️ AWS: EC2, Fargate, Serverless (Lambda), SQS/SNS, EventBridge, S3; ✔️ GCP: Cloud Run, BigQuery, Load Balancing. Database & High-Performance Search: ✔️ SQL/NoSQL: PostgreSQL, MySQL, MariaDB, MongoDB, SingleStore; ✔️ Caching & Discovery: Redis (Pub/Sub), ElasticSearch, Memcache. DevOps & Infrastructure: ✔️ Docker (Expert); ✔️ Laravel Forge/Vapor/Envoyer; ✔️ CI/CD (GitHub Actions, Jenkins). Core Competencies: ✔️ AI Orchestration & LLM Integration. Engineering intelligent systems using OpenAI (GPT-4o), Claude, and AWS SageMaker for automated content generation, sentiment analysis, and conversational AI (Telegram/Slack/Discord). ✔️ High-Scale Cloud Architecture. Designing and deploying resilient, serverless infrastructures on AWS Fargate and Google Cloud Run. Expert in auto-scaling, load balancing, and handling high-traffic surges for rapidly growing startups. ✔️ Enterprise E-Commerce & FinTech. - Payment Systems: Seamless integration of Stripe, PayPal, Braintree, and specialized providers like LiqPay. - ERP/CRM Sync: Deep-level integration with HubSpot, E-Conomic, and Uniconta. ✔️ Advanced Microservices & Backend Engineering. Architecting distributed systems and microservices using Laravel. Expert in background data processing via complex queue management (SQS/Redis) and scheduled task orchestration. ✔️ Full-Cycle Platform Development End-to-end engineering of bespoke CRMs, multi-vendor marketplaces, and high-performance SaaS applications using the TALL Stack and Filament PHP. Feel free to contact me about projects of any complexity. I guarantee that the work will be done efficiently and on time.