10/07/2026 updated
100 % available
Senior Full-Stack Developer | Mobile & AI engineer
Zemun, Serbia
Only remote
B.Sc. in Software EngineeringFlutterJavaScriptAndroid Software DevelopmentIOS ApplicationsPython (Programming Language)BlockchainNext.jsReact.jsFull Stack DevelopmentReact Native
I’m a Senior Full-Stack and Mobile Developer with 10+ years of experience building web applications, mobile apps, SaaS platforms, APIs, and business automation solutions.
My main stack includes React, Next.js, Node.js, Python, FastAPI, PHP, WordPress, Shopify, Flutter, React Native, PostgreSQL, MySQL, and third-party API integrations.
I also work with AI and automation, including AI agents, LLM integrations, OpenAI API, n8n, Make, CRM integrations, and WhatsApp automation.
I can handle the complete development process, from planning and architecture to frontend, backend, deployment, optimization, and ongoing support.
I focus on clean code, scalable architecture, strong performance, clear communication, and practical solutions that solve real business problems.
If you have an idea, an existing system that needs improvement, or a process you want to automate, I can help turn it into a reliable working solution.
Experience
Professional experience0 - 5 years
Freelancer since2018
Languages
GermanBasic knowledgeEnglishFluentSerbianNative speaker
Project history
•
Led delivery of a multi-tenant SaaS platform using React, Next.js, Node.js, PostgreSQL,
and AWS, supporting 5,000+ active users across enterprise environments and high
throughput transactional workloads while maintaining responsive customer
experiences during peak operational periods.
•
Upgraded frontend architecture improvements through reusable React components,
SSR strategies, and shared UI patterns, reducing duplicated implementation effort
across 3 frontend architecture areas and improving release consistency across
customer-facing products.
•
Architected backend services with NestJS and event-driven communication, separating
onboarding, billing, and customer operations into 3 independently deployable
capabilities that reduced release coupling and improved deployment flexibility.
•
Executed fintech workflows integrating Stripe and payment APIs, supporting 5 core
payment operations: subscription billing, invoice generation, reconciliation, payment
lifecycle management, and recurring revenue operations.
•
Streamlined asynchronous processing, queue orchestration, and caching strategies
using RabbitMQ and Redis across 2 critical infrastructure layers, resolving message
backlog scenarios during peak traffic and improving processing reliability under
production load.
Built enterprise AI products and automation systems for 3 industry sectors-financial
services, healthcare, and SaaS-using Python, FastAPI, React, PostgreSQL, and Azure.
•
Engineered production-grade RAG systems across 5 pipeline stages-ingestion,
transformation, embedding, retrieval, and indexing-improving retrieval quality and
reducing irrelevant context returned in production workflows.
•
Built 2 AI-assisted capabilities-document review and enterprise knowledge retrieval
reducing dependency on manual document analysis and accelerating access to
business information.
•
Created document intelligence pipelines across 3 processing stages-OCR, contextual
retrieval, and LLM processing-accelerating document analysis and improving
structured information extraction.
•
Architected and executed agent orchestration workflows across 3 control layers-tool
enabled AI agents, controlled execution paths, and multi-step business automation.
•
Built evaluation and validation mechanisms across 3 quality areas-prompts, retrieval
outputs, and response consistency-to improve production readiness of AI-integrated
systems.
•
Introduced 3 governance layers-governance controls, approval checkpoints, and
human-in-the-loop validation workflows—improving operational trust and reducing
incorrect AI-generated outcomes in regulated environments.
Built customer-facing B2B SaaS and subscription-based e-commerce platforms using
React, Next.js, Node.js, TypeScript, and PostgreSQL.
•
Led implementation across 5 customer journey workflows-onboarding, account
management, subscription, checkout, and order workflows-owning delivery from
technical design through production rollout and stabilization.
•
Created frontend and backend capabilities across 3 operational areas-transactions,
inventory synchronization, and real-time order consistency.
•
Architected and integrated payment infrastructure using 3 payment providers-Stripe,
PayPal, and Adyen-enabling recurring billing and secure international purchasing
experiences.
•
Provided integrations across 4 ecosystem areas-CRM, ERP, logistics, and marketplaces
supporting end-to-end business operations.
•
Collaborated with 2 cross-functional teams-product and design-to transform customer
requirements into scalable product releases.
2 / 4
•
Improved responsiveness through 4 optimization areas-frontend optimization, caching
strategies, database tuning, and API improvements-reducing average page-load time by
17%.
•
Applied 3 authentication and authorization frameworks-OAuth 2.0, JWT, and RBAC
across customer-facing applications.
•
Contributed to conversion improvements that increased customer engagement and
checkout completion rates by approximately 11%.