Fullstack Engineer

Why Halcy? Halcy is a travel app built on taste, that works for the entire group. It surfaces the places worth travelling for - restaurants, hotels, bars and experiences - and gets you there. Underneath is the hard part: a whole group planning live, agents that research, compare and act across the travel ecosystem, and a sense of taste that gets sharper with every trip. We want to bring more adventure into people's lives. We're looking for someone who shares that ambition, and who's excited to help build the company that delivers it. Who you (probably) are

• High on curiosity. Low on patience.
• High on autonomy. Low on ego.
• High tolerance for complexity. Low tolerance for repetition.
• Suspicious of process. Religious about pace.
• Speed to 80% equalled only by the drive to optimise the last 20%.

What you (ideally) bring

• Must have
• Our stack, or close to it. React, TypeScript, Tailwind, Postgres, Supabase edge functions. Production experience across most of it.
• Mobile, iOS and Android. Capacitor or React Native, store submissions, TestFlight, signing, release builds.
• You build with agents every day. You know their failure modes and when to intervene.
• Speed to value. You pick up an unfamiliar API, domain or language and ship something real with it the same week.
• Bonus
• Consumer products. You have shipped to ordinary people, at consumer quality bars.
• AI-native product work. LLM features in production: tool calling, streaming, evaluation, and the cost and latency mechanics that come with them.
• Multiplayer applications. Realtime shared state, presence, conflict resolution.

What you will (mostly) do Build the multiplayer, agentic layer travel has never had. A whole group editing one live plan while an assistant researches, compares and reasons alongside them. Ship features end to end, every week. Schema, edge function, UI, and the analytics to know whether it worked. Meta-code. Most of our output goes through agents. Build the rules, commands and routines they run on, for your own leverage first and the team's after. Know what could break before it does. Migrations that have to stay compatible with frozen TestFlight builds. RLS gaps. Provider rate limits. AI spend per user. You find these while they are still cheap. Shrink the rest of the team's blind spot. Hold the whole system in your head, stay paranoid about one line of it, and go three layers down to sort it out when something smells wrong. Pick your own work from what the product obviously needs. Nobody here will hand you a ticket. Benefits

• Compensation €60,000–120,000, calibrated to experience.
• Equity Four-year vest with one-year cliff.
• Location Hybrid, based in Stockholm.
• Ownership Real ownership over a domain from day one.
• The work An opportunity to solve a universal and meaningful problem.