Founding Software Architect

Job description

📍 Barcelona, Spain — hybrid 💼 Full-time employment 📈 0.5–1% equity About Our Client Our client is an early-stage technology company building an AI-native platform for complex hardware engineering. The platform brings system architecture, requirements, verification, engineering workflows, and technical decisions into one traceable environment. It provides engineers and AI agents with the context required to design, validate, and evolve complex hardware systems more effectively. The technology can be applied across aerospace, defence, robotics, transportation, semiconductors, and other advanced engineering industries. The product is already live and used by customers. The company is now preparing for its next stage of growth, including a planned seed funding round in autumn 2026. The team currently consists of two founders supported by an external engineering team. This hire will become the first senior technical leader brought fully in-house. About the Role Our client is looking for a deeply hands-on software architect who can become the technical reference point for the product and the future engineering team. You will work directly with the founders, take ownership of the existing architecture and production environment, and gradually assume responsibility currently held by an external software architect. This is not an enterprise architect or people-management position. You will spend most of your time designing, building, reviewing, debugging, and shipping production software. You will also own the decisions behind the implementation: how services and data models should be designed, which technologies are appropriate, where strong foundations are necessary, and where a simpler solution is better. As the company grows, you will help hire the first internal engineers, establish the engineering culture, and have the opportunity to develop into a broader technical leadership role. What You Will Do - Take technical ownership of the existing product and production environment - Design and evolve the backend architecture, APIs, and relational data model - Build product capabilities across backend, frontend, infrastructure, and AI systems - Review code in depth and maintain ownership of technical quality, including AI-generated code - Define practical standards for architecture, testing, security, observability, releases, and documentation - Improve development speed without creating unnecessary complexity or operational fragility - Work directly with founders and customers to turn ambiguous needs into product and technical decisions - Explain technical alternatives, trade-offs, risks, and failure modes clearly - Support the transition from an external development team to an internal engineering organization - Help assess, hire, mentor, and set the technical bar for future engineers What We’re Looking For - 6–10 years of professional software engineering experience - Strong hands-on experience owning production software systems - Particular depth in backend architecture and relational database design - Strong TypeScript experience, ideally across both backend and frontend - Experience designing APIs, services, modules, integrations, and clear system boundaries - Strong knowledge of PostgreSQL or another relational database, including data modelling, performance, migrations, integrity, and access control - Experience with React, Next.js, or another modern frontend framework - Practical experience with Docker, cloud deployment, CI/CD, monitoring, and production debugging - Evidence of taking ambiguous product problems from initial requirements through production and ongoing operation - Experience making technical decisions and explaining the alternatives and trade-offs behind them - A production mindset covering security, testing, observability, reliability, performance, and maintainability - Experience working in an early-stage startup, scale-up, or similarly high-ownership environment - Clear and concise technical communication in English - Based in Barcelona or genuinely willing to relocate - The right to work in the EU without visa sponsorship Our client values demonstrated engineering judgement more than an exact technology checklist. However, this is a backend- and data-intensive role. Profiles built primarily around frontend development are unlikely to be a match. The Person Who Will Succeed in This Role You are likely to enjoy this opportunity if you: - want to build rather than manage from a distance; - are comfortable working without a detailed roadmap or established engineering organization; - investigate systems methodically instead of replacing components you do not immediately understand; - have strong opinions but can change them when the evidence changes; - can challenge founders constructively and explain the business impact of technical decisions; - communicate risks early and bring possible solutions; - care about customer outcomes as much as implementation; - actively follow new engineering practices and continue strengthening your technical foundations; - want your decisions to shape both the product and the future team. Nice to Have - Experience as a Founding Engineer, Staff Engineer, Principal Engineer, Tech Lead, or hands-on Software Architect - Experience building a product from an early stage and supporting it through growth - Experience developing complex B2B or enterprise software - Experience building AI-powered features, RAG, semantic search, agentic systems, or MCP-based integrations. - Direct work with customers or industry partners - Experience establishing code-review, testing, documentation, or engineering standards - Meaningful open-source contributions or technically substantial personal projects - Interest in aerospace, defence, robotics, automotive, railway, semiconductors, or other advanced engineering industries - Spanish or Catalan language skills What Success Could Look Like in the First Year You will have: - taken ownership of the existing architecture and production environment; - built a strong working relationship with the founders and current external engineering team; - delivered important product capabilities from design through production; - improved the backend architecture and data model where necessary; - established clear standards for code review, testing, releases, observability, and AI-assisted development; - reduced operational and architectural fragility; - helped transition engineering knowledge and responsibility in-house; - contributed to hiring and developing the first members of the internal engineering team. Location and Working Model This is a hybrid role based in Barcelona, with regular in-person collaboration with the founders and future engineering team. Our client focuses on ownership and outcomes rather than tracking working hours. The exact working pattern can be discussed, but the position is not intended to become permanently remote. Candidates currently outside Barcelona may be considered if they have a realistic relocation plan and can work in Spain without visa sponsorship. Defence-Related Work Our client’s platform supports complex hardware engineering, including aerospace and defence applications. Candidates must be comfortable working with responsible defence organizations supporting European security. Our client applies explicit ethical boundaries when selecting customers and projects. Some future projects may require eligibility for security clearance, which can depend on citizenship. This will not necessarily apply to every project, but relevant citizenship and clearance eligibility may need to be confirmed during the process. Interview Process 1. Introductory conversation with the recruitment team 2. Technical interview with our client’s founding team 3. Practical technical exercise based on a real product problem 4. Final in-person meeting in Barcelona The process is designed to understand how you reason, investigate problems, use AI tools, and defend technical decisions—not how well you memorize framework-specific answers.