Igor Stajic
Verified Expert in Engineering
Node.js Developer
Novi Sad, Vojvodina, Serbia
Toptal member since July 1, 2019
Igor is a software developer with 12+ years of experience, focused on JavaScript/TS, mainly React and Node.js, with an AI-first workflow built around Claude Code and Cursor. Most code he ships today is built with LLMs in the loop, from end-to-end features to large refactorings. He's experienced in auditing and hardening AI-generated codebases, building AI-powered products (LLM integrations, agentic workflows, RAG), and delivering enterprise-grade platforms from MVP to release and maintenance.
Portfolio
Experience
- API Integration - 12 years
- JavaScript - 12 years
- Node.js - 12 years
- Express.js - 10 years
- REST APIs - 10 years
- React - 10 years
- TypeScript - 8 years
- System Architecture - 8 years
Preferred Environment
MacOS, Visual Studio Code (VS Code), Claude Code, Codex
The most amazing...
...project I've worked on is the digitization of Pfizer's site intelligence processes.
Work Experience
Senior React Developer
Pfizer
- Digitized the site intelligence and selection workflow by building a streamlined web-based application, replacing the previous manual Excel-based process.
- Architected and built a React application from scratch using MUI.
- Worked in a team with other Toptal developers. Used Jira for task management and sprint tracking.
Full-stack JavaScript Developer
Freelance
- Contributed to many projects using React, Ember.js, and Node.js.
- Worked mostly with startups, in small teams, and involved in all of the project lifecycle phases.
- Architected and developed complex solutions using both NoSQL and SQL databases.
- Integrated and worked with many third-party API services like Stripe, Algolia, Intercom, Zendesk, FirstPromoter, social network APIs, and more.
- Used both the AWS and Google Cloud Platforms.
Full-stack Developer
Lattify LTD
- Built full-stack features end-to-end on a multi-tenant B2B training platform, including an AI guide processing pipeline, async multi-language translation with real-time status polling, and locale-aware content delivery per employee.
- Collaborated cross-functionally with back-end engineers and a UX designer to align API contracts, data models, and UI from spec to production.
- Used Next.js (App Router), TypeScript, React Query, Node.js, REST APIs, Auth0, and PWA.
Full-stack JavaScript Engineer
Hartree Works LTD
- Built a Node.js API MVP for manipulating RSS feeds.
- Built a Chrome extension MVP for reading and manipulating Google Calendar data.
- Worked and communicated directly with the founder on defining the features and architecting solutions based on ideas.
Full-stack React/Node.js Developer
Talis Protocol
- Worked on new features and bug fixes on a React application's existing front end (Next.js).
- Migrated a Node.js API and GraphQL resolvers from using DynamoDB to MongoDB with Mongoose.
- Built migration scripts for transfers from different third-party API providers.
Senior Full-stack JavaScript Developer
Support.com
- Worked as part of the core development team on the main SaaS product.
- Designed and developed integrations with complementary third-party systems using OneTrust, HubSpot, and Twilio.
- Developed data migration scripts for different external systems, importing over 100k user records.
- Worked in a fully remote team, interfacing with QA, UX, product design, and DevOps teams.
- Performed design and code reviews, shared knowledge, and contributed to system architecture design decisions.
- Worked on implementing unit and functional testing.
CTO
Home2Market
- Worked on rewriting and redesigning a web SaaS platform called Home2Market.
- Architected and built the back end using Node.js, Restify, and Firebase.
- Implemented many SaaS platform-related features and worked on integrating multiple third-party APIs.
- Architected and built a web application using React and Node.js.
- Implemented a new design and many features needed for the SaaS platform that real estate agents used to manage and market their listings.
- Committed to all stages of the development for an enterprise-grade platform—from developing an MVP, reviewing the UI designs, technology choices, getting it ready to release, releasing the platform, and maintaining it.
- Hired and managed two external contractors for some short-term work, supervising their work and performing code reviews.
Lead Developer
TMNS Serbia (now Devoteam)
- Built a SaaS product's front end, from the ground up, using Ember.js.
- Worked with other team members, provided guidance, and helped them out when they were stuck.
- Conducted code reviews and enforced coding standards and best practices.
- Introduced junior developers to the Ember.js framework.
- Worked with product owners on defining the roadmap and breaking down user stories.
- Converted an existing AngularJS application to Ember.js.
- Grew the team from two developers to two front-end team of 2-3 developers, and built the back-end team over a two-year period, interviewing and hiring people as we expanded. I was the development lead and managed both front-end teams at the end.
Experience
Home2Market
iCouch
uBegin
Love Wall
Education
Bachelor's Degree (Honors) in Electrical and Computer Engineering
University of Novi Sad, Faculty of Technical Sciences - Novi Sad, Serbia
Certifications
Professional Scrum Master I
Scrum.org
Skills
Libraries/APIs
React, Node.js, React Redux, API Development, Playwright, REST APIs, jQuery, Stripe, Google Maps, Google Maps API, Claude API, WebRTC, Zod, Stripe API, Twilio API, AWS Amplify
Tools
GitHub, JSX, NPM, Expo, Claude, Claude Code, Git, NGINX, Chrome Developer Tools, Auth0, TestFlight, TanStack Router, Codex, Capacitor, Flow, Jira, Webpack, Docker Compose, GitLab, Bamboo, Trello, GitLab CI/CD, Bitbucket, Figma, Mongoose, Prisma, SendGrid
Languages
TypeScript, JavaScript, HTML5, ECMAScript (ES6), HTML, SQL, GraphQL, CSS, ES7, Sass, SCSS, Less, XML, Python, Swift
Frameworks
Next.js, Ember.js, React Native, Express.js, Material UI, Redux, Bootstrap, Jest, Tailwind CSS, NestJS, i18next, Fastify, AngularJS, Angular, React-Bootstrap, Electron
Paradigms
API Architecture, Mobile Development, Cross-platform, Role-based Access Control (RBAC), REST, Scrum, HIPAA Compliance, Testing, Automated Testing, Database Design, Model View Controller (MVC), Functional Programming, DevOps, Real-time Systems, UI Design
Platforms
Firebase, Amazon Web Services (AWS), Visual Studio Code (VS Code), Mobile, Linux, Google Cloud Platform (GCP), Vercel, AWS Lambda, iOS, Twilio, Replit, Docker, MacOS, Heroku, Android, HubSpot, Clerk
Storage
Firebase Realtime Database, PostgreSQL, MongoDB, MySQL, JSON, Database Architecture, Amazon S3 (AWS S3), SQLite, Redis, Elasticsearch, Cloud Firestore, Databases, Google Cloud, Amazon DynamoDB, Neo4j
Industry Expertise
Accounting, Healthcare
Other
Minimum Viable Product (MVP), Front-end, Full-stack, Full-stack Development, Code Review, Source Code Review, Web Development, APIs, Architecture, MERN Stack, CTO, Startups, Application State Management, Responsive Web Apps, Software Architecture, Mobile App Development, Early-stage Startups, AI-generated Code, AI Tools, Large Language Models (LLMs), Coding, Software Design, Scalability, Web Scalability, Mobile Apps, Product Engineering, GitHub Actions, Back-end, Cross-platform App Development, Web Applications, Authentication, Authorization, Webhooks, AI Development, Software as a Service (SaaS), SaaS, Website Performance, User Interface (UI), API Integration, Responsive UI, CI/CD Pipelines, Maps, Serverless, Storybook, Vite, UI Testing, Leadership, Artificial Intelligence (AI), Cloud Storage, Supabase, Supabase Auth, Cloud Infrastructure, System Architecture, AI Agents, Cursor AI, HIPAA, AI Integration, User Experience (UX), Consulting, Performance Optimization, Auditing, Code Auditing, EAS, Cloudflare, Resend, Bun, App Store Acceptance Process, Native Mobile Apps, Multi-tenant SaaS, Payment APIs, Payments, Email, SQL Server, Data Modeling, Google Tag Manager, SOLID Principles, ParcelJS, Interviewing, Hiring, Computer Science, Software Engineering, RSS Feeds, Podcasting, Chrome Extensions, OpenAI, HIPAA Electronic Data Interchange (EDI), General Data Protection Regulation (GDPR), Google Play Store, App Store, Security, CRM, QR Codes, Real-time Data, Scheduling, Message Queues, Chatbots, Prompt Engineering, AI Engineering, Concurrency, Image Recognition, AI Automation, Lovable, Videos, Streaming
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