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Stefan Krstic

@stefankrstic1

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Software engineer building React web and mobile products, including a tutoring app with real-time voice and LLM tools.

Serbia

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At Ateš Soft, I led the modernization of a React.js web portal, replacing legacy AngularJS components while preserving existing functionality. I also built a React Native app for field workers with WebSocket synchronization and offline-first capabilities.

At Ncoded Solutions, I delivered four React.js products across real estate, fitness, peer-to-peer rentals, and workspace rentals. I built chat, search and filtering, and booking workflows that were reused across projects.

I'm currently building Magična Škola, a tutoring app for children with a shared whiteboard, real-time voice interaction, and agentic LLM tool-calling. In freelance projects, I've also developed modular interfaces for fleet management, maintained a nutrition-tracking app, and contributed to mobile and web products.

Experience

Work history, roles, and key accomplishments

Current

Personal Project Developer

Current

Magična Škola

Developing a tutoring web application for children with a chat interface, shared whiteboard, and real-time voice interaction. Backend uses agentic LLM tool-calling with OpenRouter and Gemini, and voice interaction uses client-side VAD with LiveKit.

React LiveKit LLM Tool Calling Python fastAPI ONNX Runtime Voice Activity Detection

Software Developer

Ateš Soft

Jan 2021 - Aug 2026 (5 years 7 months)

Led modernization of a React.js web portal, migrating legacy AngularJS components to a modern architecture. Built a React Native mobile app with real-time sync and offline-first capabilities, and contributed to a Flutter/.NET module for industrial workforce platform.

React React Native AngularJS Flutter .NET Redux Redux Saga WebSockets Offline First Local Persistence Operation Queues

Software Developer

Ncoded Solutions

Dec 2020 - Dec 2021 (1 year)

Delivered four React.js products across different domains within a year, including real-estate investment, trainer-client video/booking, peer-to-peer rental, and workspace-rental platforms. Built asynchronous chat systems, multi-criteria search, and booking workflows.

React JavaScript TypeScript Redux Redux Saga REST WebSockets Component Standardization Reusable Hooks

Software Developer

TrainMe Online

Nov 2019 - Dec 2020 (1 year 1 month)

Built a trainer-client fitness platform in Angular 9 and Node.js, with real-time chat and training/meal-plan management, in a team of three.

Angular NodeJS JavaScript TypeScript REST WebSockets

Freelance React Native Developer

Sprowt

Developed a React Native app with real-time chat, video calls (Twilio), and calendar scheduling, and contributed to the companion web platform.

React Native Redux Twilio

Freelance React Native Developer

Fitsprite Nutrition

Maintained and modernized a React Native nutrition-tracking app, adding automatic food recognition from photos, barcode scanning, and Apple Health/Samsung wearable integration.

React Native Image Recognition HealthKit

Freelance Frontend Developer

Logitrack

Developed a React.js frontend for a fleet and container management platform, designing a modular, accessible UI component system with TailwindCSS, shadcn/ui, and Radix UI. Used Zustand and TanStack Query for state and data synchronization, and React Table for data-heavy views.

React Tailwind Shadcn Ui Radix UI Zustand Tanstack Query React Table React Hook Form Zod

Freelance React Developer

Surgeprint

Developed a React web application for a print-on-demand platform, including a custom in-browser image editor using React Konva for precise print-layout design.

React React Konva