Karlo Volf

Frontend Engineer

EdTech platform · joined as the 4th engineer, pre-launch · remote

Joined an EdTech startup at MVP stage and co-built it to 400K+ users over two years.

• –Co-built and scaled the platform from MVP to 400K+ users through feature development and UX improvements — my longest visible engineering tenure on the team, joined about a year before public launch
• –Primary owner of the in-browser code editor used by 50K+ students: a sandboxed HTML/CSS/JS playground with live preview, console capture, resizable panes, and a custom infinite-loop guard that caps runaway while(true) before it freezes the tab
• –Highest-volume contributor to the main React/TypeScript app — 799 commits across ~15 engineers, touching about half of all source files
• –Built the end-to-end share feature — schema, REST endpoints, frontend, cross-window postMessage embedding — that drove viral organic growth

React · TypeScript · Next.js 14 · Redux Toolkit · CodeMirror 6 · Node/Express · PostgreSQL · Cloudflare Pages

Sole Product Designer & Frontend Engineer

football match-analysis SaaS · for youth-football coaches and parents

Designed and single-handedly built the complete frontend of a video-based match-analysis platform — from UX research to production code.

• –Owned everything except the backend API: UX research, product and interaction design, and the entire React 19 + TypeScript implementation — for non-technical users
• –Built a resumable chunked upload engine for multi-GB match videos to Cloudflare R2 — 25 MB multipart chunks with 3 parallel uploads, per-part exponential-backoff retries, transparent presigned-URL expiry recovery, and localStorage-fingerprinted resume after a crash or reload
• –Designed keyboard-first in-video action tagging: timestamped clip capture with single-key shortcuts (S start/stop, G goal, A assist, 1–9 player select) so coaches can annotate matches at speed
• –Built a 5-level progressive data-completeness system that unlocks insights as coaches tag more — a deliberate UX answer to the empty-dashboard cold-start problem

React 19 · TypeScript · RTK Query · shadcn/ui + Radix · Tailwind 4 · Clerk · Cloudflare R2 · Zod · i18next

Lead Fullstack Engineer

influencer marketing platform · live with real users since March 2026

Empty repo to live product in two months — architecture, backend, frontend foundation, and the core product flows.

• –Took an admin-curated influencer marketing platform from empty repository to a live MVP in ~2 months as lead and primary engineer (~68% of 662 commits), then carried it through launch and months of real-user operation
• –Architected the entire stack: a type-safe Turborepo monorepo (React 19 + Vite, Express + Drizzle/PostgreSQL) with an OpenAPI-driven codegen pipeline — backend route annotations generate the typed frontend client, end-to-end type safety across the API boundary
• –Built multi-platform social OAuth (Instagram, Facebook, TikTok): S256 PKCE on TikTok, DB-backed single-use CSRF state, and AES-256-GCM encryption at rest for OAuth tokens with PBKDF2 key derivation
• –Built the live social-metrics pipeline against Facebook/Instagram and TikTok APIs — followers, engagement, reach, audience demographics — with a daily cron sync doing token refresh-rotation, batching, and exponential backoff with jitter
• –Shipped the most complex product flows end-to-end: admin influencer selection with per-influencer pricing (3-step state machine, live cost rollup), a draft-persisting campaign wizard, messaging with read tracking, and a multi-stage content-approval queue

TypeScript · Node/Express · PostgreSQL + Drizzle · Supabase (Auth, Storage, RLS) · React 19 · RTK Query · Turborepo · OpenAPI codegen · Railway + Vercel

Software Engineer (contract, via agency)

web platform for the world’s largest esports tournament

Commerce, gamification, and CMS work on a high-traffic tournament platform — Next.js 16, GraphQL, Shopify.

• –Migrated the Strapi CMS layer from REST to GraphQL: built the frontend GraphQL client and shared fragments, migrated the homepage/game/qualifier fetchers, and scoped queries per view — cutting data payloads ~80% and improving load times; wrote the team's REST/GraphQL parity guidelines
• –Built and maintained Shopify Storefront API integrations — orders, products, delivery, cart/checkout, collection filtering, search, pagination — plus the client's match/stream data services
• –Implemented gamification with the team: leaderboards (server-side search/pagination, a privacy refactor stripping user IDs from client-facing ranking data), quests with XP and login streaks, a rewards points-store with checkout and order history, and Pick'em

Next.js 16 (App Router) · React 19 · TypeScript · GraphQL/Apollo · Strapi 5 · Shopify Storefront + Admin API · AWS Cognito · TanStack Query · Tailwind

Web Developer → Lead Developer → Technical Product Manager

agency · owned infinum.com + academy.infinum.com · Zagreb, hybrid

Owned Infinum's flagship websites for five years — signature motion design, a 58-block design system, and a team-of-8 leadership role.

• –Led development of infinum.com and academy.infinum.com through a full redesign — top contributor on both codebases (~4,286 commits and 58% of the redesign repo; ~1,986 commits on the original site) and the team's primary PR reviewer and integrator (1,400+ merges, 124 versioned releases)
• –Engineered the sites' signature motion design: a scroll-driven showreel with battery-aware low-power mode, a bespoke cursor-takeover reveal, Barba.js SPA-style page transitions with an animated logo loader, GSAP + ScrollTrigger across ~16 modules, Lottie hover animations, and Spline 3D
• –Built a 58-block, manifest-driven Gutenberg design system on a dependency-injection PHP architecture (234 service classes, strict types) — an in-house component library, not an off-the-shelf theme
• –As Technical Product Manager (9 months), managed a cross-functional team of 8 — engineers, QA, designer, DevOps, data analyst — through 1:1s, code reviews, mentoring, and architecture planning, and designed a project-estimation framework adopted company-wide

React · PHP 8 (DI, strict types) · WordPress multisite/Gutenberg · GSAP + ScrollTrigger · Barba.js · Lottie · Spline · Webpack · GitHub Actions

Lead Frontend Engineer

AI data platform · text-to-SQL for non-technical teams · remote

Architected the frontend of an AI data platform — auth engine, Stripe billing, a 31-component design system, and the full admin surface.

• –Led frontend architecture for a text-to-SQL AI platform: owned the foundations — auth, billing, design system, admin — at ~76% of the codebase, and co-built the core product feature
• –Architected the auth/session engine: a NextAuth + Firebase hybrid with silent, loop-guarded token refresh on 401/403/410, edge-middleware route protection, and permission-string RBAC
• –Built the complete monetization surface: Stripe embedded checkout, tiered plans, real-time usage metering with quota-aware, permission-gated upgrade prompts, and trial-lifecycle gating at the layout level
• –Designed and built a 31-component design system on Radix + CVA with a custom Tailwind token and typography scale — including extending tailwind-merge so the custom type scale composes safely

Next.js 14 (App Router/RSC) · TypeScript · NextAuth + Firebase · Stripe · Radix UI · Tailwind · TanStack Table · CodeMirror

motion & interaction

Motion in service of comprehension, not decoration. The Infinum showreel, cursor-takeover reveal, and Barba.js page transitions were mine — GSAP, ScrollTrigger, Lottie, Spline. This page works the same way: the lens toggle above uses motion to explain state, not to decorate it.

design systems

Tokens, typography scales, and primitives that keep whole products consistent: the 58-block Infinum Gutenberg system, the 31-component Sulie system on Radix + CVA, and Trequa's shadcn/Radix system.

“I hired Karlo at Auditorium when our product was still an MVP, and he quickly became one of our most impactful engineers. Karlo pairs strong product sense with deep technical skill.”

Philipp Muellauer — Founder, Auditorium

“Karlo is a highly reliable, product-oriented engineer who takes real ownership. … He became someone I could trust to own projects, ship autonomously, and deliver results at speed.”

Soroush Saffari — Engineering Lead, Auditorium

“What truly set him apart was his exceptional sensitivity to design and user experience. … He raised the quality of the product not only through his code, but through critical thinking and a genuine care for the user experience.”

Emanuel Loborec — Principal Designer

“He's a strong software engineer with solid computer science fundamentals, clean architecture, and a keen eye for detail. … Cheerful, true and genuinely great person to work with. I would like to work with him again.”

Tomislav Vukić — Head of Torneo at Sofascore

“He delivered high-quality work, was proactive in solving problems, and always open to discussing how things could work better. … I'm not someone who says this lightly, but he's truly someone you can rely on.”

Renato Mandić — Freelance Web & Product Designer