available for new opportunities · Mostar / Zagreb

MARIO ROZIC

>

Frontend engineer with 8+ years shipping production React & TypeScript — real-time betting platforms, oil & energy dashboards, healthcare, e-commerce. Now building with AI in the loop.

enter the build get in touch
0years in production
0companies shipped for
0live betting feature shipped solo
0junior devs led & mentored

01 whoami

mario@portfolio:~
$ whoami
mario rozic — frontend-focused software engineer

$ cat focus.txt
▸ complex dashboards & data-heavy UIs
▸ real-time features (sockets, live data)
▸ scalable state: Zustand · Jotai · Redux
▸ testing culture: Vitest · Storybook · Jest
▸ AI-assisted engineering + AI product features

$ cat now.txt
▸ Web Developer @ Diplomat Tech
▸ modernising a legacy JS betting platform → TypeScript

$ ls hobbies/
basketball/  gym/  snowboarding/  travel/  books/  board-games/  seinfeld/
$

I like the hard end of the frontend: interfaces where data changes every second, where a bug costs real money, and where the codebase has years of history behind it.

I introduced testing to a codebase that had none, led teams of juniors, talked directly to customers about technology choices, and shipped a live player-betting feature solo with almost no margin for error.

I started on the backend — Go microservices, CockroachDB, sockets — so I still think about the full path a pixel takes to the screen.

02 experience

Jun 2025 — now

Web Developer @ Diplomat Tech

Mostar · on-site

  • High-traffic betting platform: live betting site plus full back office.
  • Introduced Vitest to a previously untested codebase.
  • Shipped a complex live player betting feature solo, real-time data, minimal margin for error.
  • Zustand and custom logging; refactoring legacy JS toward TypeScript.

ReactZustandVitestTypeScript

Jul 2023 — Apr 2025

Web Developer @ Three60 Energy

Remote

  • Dashboards for tracking wellbores, oil transport and renewable energy.
  • Every component isolated and tested in Storybook; heavy MUI Joy + ECharts.
  • Moon monorepo, Jotai + TanStack for tables and queries.
  • PostHog analytics, OpenAI chat; backend with Node, Elysia, Drizzle. Direct customer contact.

ReactStorybookJotaiEChartsElysiaDrizzle

Jul 2021 — Jun 2023

Web Developer @ Q agency

Remote

  • Led the frontend team on a BYOD virtual assistant with intricate calendar/schedule features.
  • Managed two junior developers on a UI/UX-heavy project.
  • Maintained a legacy healthcare app; helped backend with Node, GraphQL, S3.
  • Built the project skeleton used to start new frontend projects.

ReactReact QueryTypeScriptGraphQLAWS S3

Jan 2019 — Jul 2021

Web Developer @ BlueHat

Remote · Doha, Qatar

  • Led a business-to-supplier transaction platform.
  • Built the supplier admin panel and a custom e-commerce shop.
  • Set up the GitHub Actions deployment pipeline; kept a long-lived legacy system stable.

ReactReact QuerySocket.ioGitHub ActionsGoogle Maps

Aug 2018 — Dec 2019

Full Stack Developer @ Spark

Mostar · on-site

  • CS:GO betting solution: split the backend into real-time communicating services.
  • Thread management and query optimisation for rapid bet calculation.

GolangDockerCockroachDBReact NativeSocket.io

03 stack

Frontend

React · Next.js · TypeScript · Zustand · Jotai · Redux · TanStack Query · MUI Joy · ECharts · Styled Components

Backend

Node.js · Express · Elysia · GraphQL · Prisma · Drizzle · MySQL · Golang · CockroachDB · Socket.io

Quality & Delivery

Vitest · Jest · Storybook · GitHub Actions · GitLab CI · Jenkins · Docker · Moon monorepos

AI

OpenAI integration in production · AI-assisted engineering workflows · Claude Code

04 projects

01

DJapp

A crowd requests songs from a DJ at a live gig. Share a six-character code, no accounts, boost a request up the queue. The DJ accepts, rejects or marks it played.

pnpm monorepoReactNode APIStorybook

↗ 02

GitHub Pulse

Turns a GitHub user's year into a readable report: contribution heatmap, streaks, weekday rhythm, byte-weighted language mix. One GraphQL round trip, server-rendered.

Next.jsTypeScriptTailwindGitHub GraphQL

↗ 03

PathFinder

Path-finding in TypeScript with both a CLI and a web interface.

TypeScriptJestCLI + Web

↗ 04

Telescope

A component-driven React playground: Vite, Storybook, Tailwind, React Query and Jotai.

ViteReactStorybookJotai

↗

05 contact

Have something hard to build?

rozic.marioo@gmail.com
github linkedin