04/01/2026 updated

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Premium member
40 % partially available

Senior Full-Stack Developer | GenAI LLM experience | Typescript, React, Next.js, Node.js, Nest.js

Zagreb, Croatia Master of Science in Electrical Engineering and Technology
Zagreb, Croatia Master of Science in Electrical Engineering and Technology

Profile attachments

CV (Spoljaric) 2026.-1.pdf

About me

Senior JS/TS full‑stack developer (front‑end focused) with 7+ years as a remote B2B contractor for clients such as Databricks, BCGX and NATO. Experience in LLM chatbots, GenAI writing platforms and data analytics tools for ML/GenAI development, evaluation and observability.

HTMLJavaScriptResearchAmazon Web ServicesUnit TestingAutomotive IndustryBusiness To BusinessCascading Style Sheets (CSS)Educational TechnologiesData ModelingAmazon DynamoDBForestryGitHubPython (Programming Language)PostgreSQLMongoDBNode.jsOAuthPrism (Software)Role-Based Access ControlE2e TestingNext.jsTeamViewerTypeScriptWeb ApplicationsWebSocketWYSIWYGIndustrial PolishingFront End (Software Engineering)ChatbotsTailwindReact.jsLarge Language ModelsCypress (Programming Language)Generative AIVue.jsFastAPIVue.jsWebpackPlaywrightData AnalyticsLogistics OperationsGraphQLMachine Learning OperationsReact ReduxApi DesignNestJSRestful ApiCucumber (Software)MochaGPTDockerDatabricks
I’m a senior full‑stack JavaScript/TypeScript developer with a front‑end focus and 7+ years of experience delivering production web applications for enterprise clients.

I work primarily as a remote B2B contractor and have contributed thousands of hours to organisations such as Databricks, BCG/BCGX, NATO, VW, Audi, DHL and TeamViewer, across domains including GenAI & LLM products, data analytics, automotive, logistics, EdTech, industrial processing and forestry.

My core stack: TypeScript, JavaScript, React, Next.js, Node.js, NestJS, Vue.js, with tools like Zustand, Redux, GraphQL, REST, Tailwind CSS, Emotion, SWR, Jest, Playwright, Cypress, Cucumber, WebSockets, AWS (Lambda, DynamoDB) and Docker.

I’m comfortable owning complex front‑end and full‑stack features end to end, from API design and data modelling to polished, performant UIs.

Recent highlights include:
  1. GenAI Chatbot for NATO – senior front‑end developer on an LLM/RAG‑powered assistant for engineers and researchers, using React, Vite, Zustand, SWR, Tailwind and Shadcn.
  2. MLflow at Databricks – senior front‑end developer work on an enterprise analytics and ML/GenAI observability platform with React, Zustand, GraphQL, Playwright and Emotion.
  3. GenAI writing platform for BCGX – senior full‑stack role on a greenfield Next.js 14 app with a collaborative WYSIWYG editor (Tiptap, Lexical, Yjs, WebSockets), RBAC/ABAC permissions (Casbin) and E2E tests (Cypress, Cucumber).
I’m experienced in distributed, agile teams, working closely with product, design and data stakeholders, and I tend to operate as a senior IC who can independently drive features from idea to release.

I work 100% remotely from Zagreb, Croatia and am interested in new freelance B2B contracts, especially around GenAI/LLM applications, complex front‑ends and data/analytics platforms.

Languages

GermanBasic knowledgeEnglishFluentCroatianNative speaker

Project history

Senior front-end developer for a GenAI chatbot

NATO CMRE

Government and Public Services

1000-5000 team member

I worked on a GenAI Chatbot powered by LLMs such as OpenAI GPT models. The Chatbot provides personalised assistance for NATO employees, such as engineers and researchers, by using a proprietary knowledge-base and RAG to enhance the context and quality of responses. As a front-end developer I utilised React, Vite, Zustand, SWR, Tailwind, Shadcn, AI Elements and other tools

Senior front-end developer for an enterprise analytics platform

Databricks

Internet & IT

>10.000 team member

Worked on Mlflow, an enterprise data analytics platform for developing models, generative AI applications, state-of-the-art experiment tracking, observability, and performance evaluation for machine learning models, and agents on the Databricks lakehouse. As a front-end developer I utilised React, Zustand, GraphQL, Playwright, Emotion and other tools.

Senior full-stack developer for a GenAI writing platform

BCG

Pharmaceuticals & Medical Technology

>10.000 team member

  • Managed a GenAI writing platform for creating structured documents and automating E2E workflows.
  • Developed an intuitive UI in Next.js 14 that enables a user-friendly experience. The core of the UI is a real-time, collaborative WYSIWYG editor where the Writer AI agent can stream LLM-generated content.
  • Built collaborative Google Docs style comments using Tiptap and Lexical editors, Yjs as a CRDT sync engine with shared data types to merge conflict-free changes from different users in real time, on top of a WebSocket back end.
  • Implemented a full-stack, E2E permissioning system based on a combination of RBAC (role-based) / ABAC (attribute-based) architecture using the Casbin authorization library.
  • Set up and implemented various e2e feature tests with Cypress and Cucumber (to support BDD Gherkin syntax).

Senior front-end developer for a data analytics product

BCG

Energy, Water & Environment

>10.000 team member

As the sole senior front-end developer I was responsible for the greenfield implementation of the entire front-end of a state-of-the-art solution based on machine learning and advanced optimization, supporting key stakeholders of a large forest industry group in strategic decision-making.

I built an advanced multi-page React dashboard with complex data visualisations and implemented UI components including charts, geo maps, tables, and Sankey diagrams using D3.js, DeckGL, Chart.js, and React (TanStack) Table.

Front-end Developer on the TeamViewer Remote app

TeamViewer

Internet & IT

1000-5000 team member

Developed new features for TeamViewer’s 2.0 UI, contributing to a web application that securely connects and controls remote devices from anywhere. I utilized React, Redux and other Web technologies like WebSocket to implement real-time updates, improving user experience and reducing latency during remote sessions.

Full-stack developer on CONIQ Cloud Application

Schenk Process

Industry & Mechanical Engineering

>10.000 team member

Contributed to the development of CONiQ Cloud, an industrial IoT platform built on AWS services for monitoring screening machines and vibrating feeders. I added new client-side features using Vue3, Vuex, Vuetify and provisioned AWS services like Lambda and DynamoDB using the Infrastructure as Code approach (IaC) and the AWS CDK. My work improved application usability and reduced system response times.

Front-end Developer on Audi on Demand platform

Audi

Automotive & Vehicle Manufacturing

>10.000 team member

Collaborated as a front-end developer on Audi’s premium car rental platform. I implemented single-page application (SPA) front-end features using Angular, and conducted code reviews to maintain high-quality standards. My contributions improved site reliability and reduced page load times, which enhanced user experience.

Front-end Developer on the Customized Solution Portal

Volkswagen Group

Automotive & Vehicle Manufacturing

>10.000 team member

Worked as a front-end developer on the Customized Solution Portal, a modern tool enabling VW partners to efficiently remodel commercial vehicles for specialized purposes in logistics, medical, and transportation sectors. Using React, Redux and Node.js I created dynamic front-end features to streamline vehicle configuration workflows. This resulted in a reduction in manual processing time for vehicle customizations.

Full-stack developer on a STEM education platform

KidzToPros

Other

10-50 team member

Designed and developed an online education platform providing STEM and sports enrichment programs for children. As a full-stack developer, I built responsive front-end features with React.js and implemented a GrapqhQL API with Apollo Client/Server. The platform supported thousands of concurrent users while maintaining high performance.

Portfolio

item-0

VW

Customized Solution Portal
https://www.customized-solution.com/en/en
item-1

Audi on Demand

A premium mobility and car rental service.
https://www.audiondemand.com
item-2

Coniq Cloud

The CONiQ Cloud app is used to monitor the condition of screening machines and vibrating feeders. The project's overall goal was to build an industrial IoT platform based on AWS services that can partially or entirely substitute the existing monitor solution.
https://coniq-cloud.com/
item-3

TeamViewer Remote

A comprehensive remote access, remote control and remote support solution that works with almost every desktop and mobile platform, including Windows, macOS, Android, and iOS.
https://www.teamviewer.com/en/campaign/new-in-teamviewer-remote/

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