Founding Engineer

About the Position

We are seeking a Founding Engineer for our fast-scaling travel startup, focusing on AI-assisted trip planning and advisor handoff. Own features end-to-end using React, TanStack Start, Supabase, and Cloudflare Workers.

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.

Responsibilities

• 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

Requirements

• 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

Nice to Have

• 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 4000-6500 EUR/month. Early-stage equity alongside salary.

Location

Warsaw, PL

We Offer

• 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.

About the Company

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.