Founding Engineer

Kilo™; Warszawa; Hybrid; PLN 245,000 - 391,000; Full time

Benefits offered by this job

Health insurance

Hybrid work model

Equity stake

Job summary

Breakneck Studio is looking for a Founding Engineer to own features end-to-end—from database schema through the server, UI, and analytics. You will shape architecture across Postgres, Supabase, and Cloudflare Workers, and integrate third‑party APIs for flights, hotels, payments, and subscriptions.

You will work directly with the founders, influence technical direction as an early hire, and help scale a fast-growing travel-tech platform while exploring OpenAI and related tooling.

Qualifications

• 3–7 years shipping production web apps, ideally at seed/Series A startup.
• Comfort being the only engineer on a feature, handling end-to-end work.
• Hands-on experience with Supabase, Postgres RLS, or pgvector and security hardening.
• Proficient in TypeScript and modern frontend frameworks.

Responsibilities

• Own features end-to-end from DB schema to UI and analytics.
• Design and evolve Postgres schemas with Supabase and RLS policies.
• Integrate 3rd-party APIs (flights, hotels, payments) with auth and webhooks.
• Build and refine LLM-powered tooling and tool-calling within the orchestration layer.
• Instrument features against a unified event schema for data-driven decisions.
• Write tests and collaborate with AI agent dogfooding.

Skills

TypeScript

Postgres RLS

Supabase

Next.js

TanStack Start

APIs integration

SSG/SSR

Tools

Next.js

Remix

SvelteKit

Cloudflare Workers

Job description

About The Team

Breakneck Studio – an incubator and accelerator scaling digital and e-commerce brands at high velocity. It's home to our Co-Found program, where ambitious founders take products from zero to market in months, not years. This is where you get hands‑on, zero‑to‑scale experience you won't find in a regular job

We are a fast‑scaling travel startup with strong product‑market fit ($1.46M ARR and growing) building Marlow AI — an AI‑assisted trip planning experience that hands off to a real human advisor to lock in the details and book the trip accurately. We are two‑sided: travelers get a consumer product that plans and books real trips, and advisors get a SaaS‑style subscription with certification and qualified leads baked into the offer.

Currently, we are looking for a Founding Engineer — someone who can own features end‑to‑end, from database schema through the server function layer, the UI, and the tracking that tells us whether it worked, and ship them without needing a hand‑off. This is one of the first technical hires on the team: your fingerprints will be on the architecture, the integrations, and the decisions that shape how we scale from here.

Get ready to

• Own features end‑to‑end: schema design → server function → UI/UX → event tracking → ship to production, using our stack of React 19, TanStack Start, Supabase (Postgres + RLS), and Cloudflare Workers
• Work directly in the Marlow AI trip‑planning flow and the advisor handoff/booking flow, across both the traveler‑facing and advisor‑facing surfaces
• Design and evolve Postgres schemas with Supabase, including RLS policies and GRANTs that actually hold up under real traffic
• Integrate and maintain third‑party APIs — flights (Kiwi Tequila), hotels (Hotelston SOAP), payments (Primer, PayPal Marketplace), subscriptions/leads (Kilo Launchpad) — including auth, webhooks, and signature verification
• Build and refine LLM‑powered tooling inside Marlow's orchestration layer (tool‑calling, streaming, prompt iteration) across OpenAI, Anthropic, and OpenRouter
• Instrument features against our unified event schema (view_item, add_to_cart, initiate_checkout, add_payment_info, payment_complete) so product and growth decisions are backed by real data
• Ship on Cloudflare's edge runtime and reason clearly about SSR vs. client boundaries in TanStack Start
• Write tests where they earn their keep, and work alongside AI‑agent dogfooding
• Take ownership of ambiguous problems, make a call, and move — this is a one-engineer-per-feature environment, not a hand‑off pipeline
• Help shape technical direction as we grow — you won't be handed a spec and a backlog forever; as the team grows, expect a voice in architecture calls and, over time, a hand in shaping the engineering team itself

We expect you to

• Have 3–7 years shipping production web apps, including at least one seed / Series A or B startup as an early hire (employee #2–15)
• Be comfortable being the only engineer on a feature, from DB migration to UI/UX, with no one else to lean on
• Have personally shipped something using Supabase, Postgres RLS, or pgvector — and understand why RLS-plus‑GRANT is non‑negotiable, not optional hardening
• Be TypeScript‑native: you write it and read it without flinching, not "I've used TS before"
• Have hands‑on experience with at least one meta‑framework (Next.js, Remix, TanStack Start, SvelteKit) and understand SSR vs. client boundaries
• Have integrated at least 10 third‑party APIs, including auth, webhooks, and signature verification — payment processors, comms platforms, legacy SOAP vendors, or similar
• Have strong communication skills and be comfortable working directly with founders and cross‑functional stakeholders

Bonus points for

• LLM tool‑calling experience: function calling, streaming, prompt versioning
• Experience on edge/Workers runtimes
• SQL beyond CRUD: window functions, CTEs, triggers
• Exposure to supervised fine‑tuning for AI

Salary

Gross salary range is 5000-8000 EUR/month. Early‑stage equity alongside salary.

Location

We have several great workspaces to choose from, including our headquarters in Vilnius and our hubs in Klaipėda and Riga.

For our Vilnius office, we follow a 4 days onsite, 1 day remote hybrid model. For roles based outside Vilnius, the work arrangement -onsite, hybrid, or remote‑depends on the specific position.

Speaking of perks

Own your wellness

Stay sharp and well in your own way – health insurance (after probation), on‑site physiotherapist, office gym, and fitness classes keep you moving. Plus 7 extra days off, 3 for weddings, hybrid work, and the freedom to work 2 months from anywhere in the world.

Boost your daily life

Every breakthrough needs a spark and our daily setup reflects that. Pet‑friendly office, fresh breakfasts, hot lunches, drawers and fridges stocked with snacks and food – for a quick bite or even a team‑cooked meal together. Rooftop and cellar events keep things lively, while 10 social clubs give space to dive into passions and try new things. Add a public transport card for Vilnius and Perks.lt perks for smoother days.

Shape your growth path

Builders never stop learning. Coaching, mentorship, training, conferences, online courses, subscriptions, books – you’ve got a €1100 yearly budget to fuel personal or team growth. You pick the path – we’ll back you all the way.

Drive global impact

This is where ambition scales. Build impact across 30+ brands worldwide. Launch bold projects. Even step in as a co‑founder – we reward those who push further. And if you bring in more great people, you get €1500 for every successful referral.

• additional conditions apply based on your residence location.