Senior Software Engineer (Full Stack)

We are looking for a Senior Full Stack Engineer to join a fast-growing, AI-native startup that is rebuilding the software behind defence, aerospace and industrial supply chains. This is a founding-engineer-style role: you will own features end to end instead of picking up tickets. You will work closely with the founders, Deployment Strategists and other senior engineers to turn messy, manual workflows into semi-autonomous processes. You will start in Warsaw with the team, and the plan is to relocate to the US (San Francisco) within about six months, with visa sponsorship and relocation fully covered. This role suits a builder with strong full-stack skills, a passion for shipping and a real wish to move to the US and grow with an early-stage company. Success here means shipping useful, clean and maintainable code that delivers real value to customers. Details: - Schedule: Full time - Location: Onsite – Warsaw, Poland (initial period, co-living provided), then relocation to San Francisco, US within ~6 months - Start: ASAP - Duration: Long-term - English: Fluent - Type of collaboration: Internal Employment - Relocation: E-2 / O-1 visa sponsorship and full relocation support to the US About the project: The company is building a back-office operating system for defence firms. It helps them find, review and bid on government RFQs, both directly with the Pentagon and as subcontractors. Every year the US government buys billions of dollars' worth of parts and products, but the process is still full of red tape, emails, PDFs and legacy systems. The company's AI-native platform ingests this fragmented data and turns manual procurement and distribution workflows into semi-autonomous processes. It pairs the platform with forward-deployed engineers who work on-site with customers until their toughest operational problems are solved. The startup is backed by a top accelerator, has 7-figure ARR and is scaling quickly across defence, aerospace and industrial sectors. You have: - Strong, genuinely full-stack experience: TypeScript/JavaScript, React/Next.js and a backend in Node.js or Python - Solid experience with PostgreSQL and SQL - A strong track record that shows engineering excellence, for example: a top technical university, a reputable software house or product company, an elite internship, competitive programming or hackathon results, or past founder experience - Builder mindset: side projects, open-source contributions, hackathons or 0-to-1 ownership - Comfort with autonomy, ambiguity and a fast-paced, demanding startup environment - Clear communication: you can explain and defend your ideas, set reliable deadlines and meet them - Customer-focused approach: you see code as a way to deliver value and you own your work end to end - Readiness to relocate to the US within about six months of starting - Fluent English Nice to have: - Experience with complex integrations, data ingestion pipelines or ERP systems - Experience with Svelte - Daily use of AI coding tools - International experience (study or work exchange abroad) - Startup or founding-engineer experience What to do: - Build and ship full-stack features end to end on an AI-native platform for defence and industrial procurement - Design and build data ingestion pipelines and integrations that turn fragmented data into structured workflows - Work closely with founders, Deployment Strategists and senior engineers to understand customer problems and solve them - Write useful, clean and maintainable code, and set a high bar for engineering quality across the team - Spot and fix bad practices that could hurt the product long term, while making smart trade-offs when needed - Set reliable deadlines, communicate progress clearly and raise concerns early - Help shape the engineering culture of a fast-growing early-stage team