Fullstack Engineer (Founding)

halcy; Stockholms kommun; Hybrid; SEK 900,000 - 1,300,000; Full time

Benefits offered by this job

Equity

Hybrid in Stockholm

Job summary

halcy seeks a skilled fullstack engineer to craft a multiplayer agentic layer and ship features end-to-end weekly. You will own frontend and mobile integration, from UI to serverless edge functions, ensuring compatibility with frozen TestFlight builds and robust analytics.

You’ll work with a React/TypeScript stack, Tailwind, Postgres and Supabase, building for iOS/Android via Capacitor or React Native, including store submissions and release processes. Hybrid in Stockholm, with equity on offer.

Qualifications

• Proficient in React and TypeScript with production experience.
• Strong experience with Postgres or equivalent databases.
• Knowledge of modern frontend tooling and Tailwind for UI.
• Mobile app development for iOS/Android (Capacitor/React Native) including app store processes.

Responsibilities

• Build multiplayer, agentic features end-to-end and ship weekly across schema, edge function, UI and analytics.
• Work with agents and define the rules, commands and routines they run.
• Address migrations and ensure compatibility with existing builds while delivering value quickly.

Skills

React

TypeScript

Tailwind

PostgreSQL

Supabase edge functions

Mobile development

React Native

Tools

Capacitor

TestFlight

Store submissions

Job description

What you will mostly do

Build the multiplayer, agentic layer travel has never had: a whole group editing one live plan while an AI books, rebooks and reasons on their behalf. Ship features end to end every week, from schema to edge function to UI to the analytics that tell you whether it worked. Meta-code, because most of our output goes through agents and you build the rules, commands and routines they run on. Know what could break before it does: migrations that must stay compatible with frozen TestFlight builds, RLS gaps, provider rate limits, AI spend per user. Pick your own work from what the product obviously needs.

Must have

Our stack, or close to it: React, TypeScript, Tailwind, Postgres, Supabase edge functions, with production experience across most of it. Mobile on iOS and Android, whether Capacitor or React Native, including store submissions, TestFlight, signing and release builds. You build with agents every day and 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, 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.

Our stack

• React, TypeScript, Vite, Supabase and Postgres, React Router, TanStack Query, Tailwind, Mapbox, Capacitor, Trigger.dev, PostHog, Sentry. We run Anthropic and Gemini side by side.

What you get

• Salary calibrated to experience, in the range above.
• Equity, four-year vest with a one-year cliff.
• Hybrid in Stockholm.
• The ceiling on what you own is however much you can carry.

Full role description: https://halcy.site/careers/roles/fullstack-engineer