Full-Stack Software Architect
Onhires
Location: Barcelona, Spain (Hybrid)
Employment: Full-time
About Our Client
Our client is building the AI platform that will redefine the future of hardware engineering.
Their product brings together system architecture, requirements, verification, and engineering workflows into one intelligent platform, helping engineering teams design and build the world's most advanced hardware systems faster and more efficiently.
From aerospace and defense to robotics, transportation, and semiconductor technologies, they're creating the AI infrastructure that will power the next generation of engineering.
This is an early-stage company where every engineer has a direct impact on the product, technology, and the future of the business.
About the Role
As a Full-Stack Software Architect, you'll work directly with the founders to help build both the product and the engineering organization from day one.
This is far more than a senior engineering role. You'll define technical direction, influence architecture, establish engineering standards, and make key product decisions while remaining deeply hands-on.
You'll own significant parts of the platform, work directly with customers, contribute to strategic decisions, and help build the engineering culture as the company scales.
If you're excited about solving difficult technical challenges, building AI-native products, and creating something from the ground up, this is an opportunity to make a lasting impact.
What You'll Do
Own product development from concept to production
Design scalable system architecture and engineering standards
Build modern full-stack applications and backend services
Own infrastructure, cloud deployments, CI/CD, and observability
Work directly with founders, customers, and industry partners
Translate customer needs into product decisions
Build AI-powered capabilities across the platform
Help establish engineering processes, code quality, and development culture
Contribute to hiring and mentoring future engineers
Represent the company at customer meetings and industry events
What We're Looking For
Required
6-10 years of professional software engineering experience
Strong experience designing and owning production software architecture
Excellent TypeScript skills across the full stack
Strong backend architecture and API design experience
Experience with React or another modern frontend framework
Deep knowledge of PostgreSQL or other relational databases
Experience with Docker, CI/CD, and cloud platforms (AWS, GCP, or Azure)
Strong understanding of scalability, security, testing, observability, and system reliability
Proven ability to take products from idea to production
High ownership and comfort working in an early-stage startup
Experience using AI development tools and modern LLM workflows
Strong communication skills and fluent English
Based in Barcelona or willing to relocate
Right to work in the EU without visa sponsorship
Nice to Have
Founding or early-stage startup experience
Experience leading technical direction or acting as a Software Architect
Experience building AI-powered products
Knowledge of RAG, vector databases, multi-agent systems, or MCP
Interest in aerospace, defense, robotics, semiconductor, automotive, or other advanced engineering industries
Tech Stack
You'll work with modern technologies including:
TypeScript
React
PostgreSQL
REST / tRPC APIs
Docker
GitHub Actions / CI/CD
AWS, GCP, or Azure
AI development tools and LLM workflows
RAG, Vector Databases, and Agentic AI
Why Join?
Become one of the first engineers shaping the company's future
Work directly with experienced founders and technical leaders
Own architecture, product decisions, and engineering standards
Build AI-native software solving real engineering challenges
Competitive salary plus meaningful equity
Help define the engineering culture and grow the team from the ground up
Additional Information
Hybrid role based in Barcelona, Spain
Applicants must have the right to work in the EU
Some projects may require eligibility for NATO security clearance due to collaboration with aerospace and defense organizations
Language learning is supported by the company