Overview

On-site | Full Time | Employment | Sofia, Bulgaria | Middle , Senior roles | React · AI

 

Fast Track is a strategy consulting and executive development firm working with CEOs and leadership teams across 35+ countries — from multi-billion corporations to ambitious startups. Now the company is building its next core business: AI-powered digital products that help executives make better decisions, faster — business diagnostics, decision support, execution tracking, and a partner platform.

We are looking for a Full-Stack Product Engineer in Sofia who will own a greenfield product build end-to-end and grow fast inside a small, high-standard engineering team.

You are looking for us if

  • owning a product end-to-end motivates you more than picking tickets from someone else’s backlog.
  • building from scratch excites you more than maintaining legacy code — the platform you’ll own is greenfield.
  • AI is already part of how you build software every day, and you want it in the product core, not on the sidelines.
  • you’d rather ship a working version this week than a perfect one next month.
  • direct, honest feedback energizes you — a flat team where a junior is expected to speak up.
  • ambiguous requirements feel like a starting point to you, not a blocker.

We are looking for you if you

  • have 2+ years of experience building software — professionally, freelance, or through a serious track record of personal projects (looking for Middle and Senior Developers) 
  • have shipped products or features to real production users (not only prototypes or coursework).
  • have a solid full-stack foundation: HTTP, databases, APIs, state management — you can reason about a system end to end.
  • are comfortable with (or can ramp up fast on) our stack: React + TypeScript on the frontend, Python + FastAPI + PostgreSQL on the backend.
  • already use AI tools daily to write code, prototype ideas, and test logic — and can show specifically how.
  • take ownership: when something you touched breaks, your first move is to understand your part in it.
  • have good communication skills in English and are ready to work on-site in Sofia, Bulgaria.

You won’t have touched everything in the stack — that’s expected. Fast Track hires for foundation and the speed to close the gap, not a checklist match.

Your diverse role will include

  • writing real code on live Fast Track products from day one — frontend, backend, integrations, whatever the product needs.
  • owning the new Partner & Affiliate Platform end-to-end: certification flows, referral attribution, commission logic.
  • building the integrations layer: CRM, calendar, ERP, webhooks.
  • translating business rules into clean, testable code, working directly with consultants and leadership.
  • prototyping fast, testing with real users, iterating on what works and cutting what doesn’t.
  • growing under the guidance of the Tech Lead — executing architectural decisions first, making them yourself over time.

Fast Track Offers:

  • Social package: gym membership and professional training
  • Paid days off in line with Bulgarian labour law
  • Full-time employment, on-site in Sofia, Bulgaria
  • A small engineering team with real feedback, real responsibility, and real work from week one
  • Guidance from the Tech Lead — you won’t be left to figure it out alone
  • Growth without waiting for a ladder: in a flat structure, harder work comes as fast as you can take it

You will enjoy

  • building products used by CEOs and executive teams in 35+ countries — work that is visible and matters immediately.
  • an AI-first engineering culture: Anthropic Claude in the product core, modern stack, no framework zoo.
  • a greenfield build with real ownership — your name on the outcome, not a line in a Jira board.
  • a fast, honest, no-politics environment where feedback is direct and growth is expected.
  • working side by side with the team in person in Sofia.

 

What we run in production today.

Read it as a filter: if most of this reads as familiar territory and the rest reads as a weekend of ramp-up, you are in range.

  1. Frontend.  React 19 + TypeScript on Vite. TanStack Query for server state, Zustand (persisted) for client state, React Hook Form + Zod with types derived from the schemas. Tailwind + CVA for styling, Axios for transport, GSAP and Framer Motion for animation, Lenis for smooth scroll. Feature-based module structure.
  2. Backend. Python 3.13 + FastAPI, async SQLAlchemy 2.0 over asyncpg, Alembic for migrations, Pydantic v2 for validation. Controller to service to repository per feature module. Magic-link OTP into a JWT cookie (no passwords, no OAuth), tiered rate limiting via slowapi, an async retry worker with exponential backoff for outbound jobs.
  3. Data.  PostgreSQL 17 on Neon (serverless, branchable). Schema is migration-driven, never hand-patched in prod. Content that drives the product is DB-backed so the frontend and the AI layer read the same source and cannot drift.
  4. AI.  Anthropic Claude SDK called directly. No LangChain, no LangGraph, no agent framework. Structured output via Pydantic schemas, prompt caching, brand and voice constraints compiled into the system prompt. AI is in the product core: scoring inputs, generating reports, compressing analysis into something an exec reads in minutes.
  5. Integrations.  Resend for transactional email, Klaviyo for the marketing lifecycle, Meta Conversions API server-side, GTM and GA4 for analytics. Failed outbound calls get enqueued and retried, not dropped.
  6. Infra and deploy.  Frontend on Vercel, backend on Render, Cloudflare for DNS and CDN. Sentry on both ends. Push to main, it ships. Preview deploys per PR.
  7. Testing.  pytest on the backend, Vitest for frontend units, Playwright for e2e against a mobile viewport. Typecheck is the build (tsc then Vite).

Direction of travel: AI moving deeper into the core of every product, and more of the build-and-ship loop automated. New tools get added when they earn it; we do not collect frameworks. You will not have touched all of this, and that is expected. We are hiring for the foundation and the speed to close the gap, not a checklist match.

 

About Fast Track

Fast Track has spent over a decade helping ambitious CEOs and their leadership teams grow as fast as humanly possible — 20,000+ executives across 35+ countries and 20+ industries. The company operates on a set of principles it actually enforces: brutal honesty, 80/20 thinking, extreme ownership, and beginner’s mind. Its digital products are the extension of that work — tools built for people with very little time and zero tolerance for anything that doesn’t earn its place in their workflow.

Fast Track says openly: it’s not for everyone. If a high pace and a high standard sound like your environment — this is a rare chance to join the product team at the start.

Interested? Let’s connect and discuss the details!

Email: alina.selnichek@sunvery.com.ua