? 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, the technology, and the future of the business.

? About the Role

As a Senior Full-Stack Software Engineer, you'll work directly with the founders and technical leadership to build a next-generation AI product from the ground up.

This is a highly hands-on engineering role where you'll own features end-to-end—from architecture and implementation to deployment and continuous improvement. You'll collaborate closely with customers, help solve complex engineering challenges, and influence both product and technical decisions.

If you're excited by ownership, modern AI technologies, and building products that solve meaningful real-world problems, this is an opportunity to make a significant impact from day one.

? What You'll Do

Own product development from concept to production

Design and build scalable full-stack applications

Develop modern backend services and intuitive frontend experiences

Translate customer needs into elegant technical solutions

Write clean, maintainable, production-ready code

Collaborate directly with founders, engineers, and customers

Review code and contribute to engineering best practices

Improve infrastructure, CI/CD pipelines, cloud deployments, and observability

Build and integrate AI-powered capabilities across the platform





Help shape the engineering culture as the team grows

✅ What We're Looking For

Required

3–6+ years of professional software engineering experience

Strong experience building production SaaS applications

Excellent TypeScript skills across the full stack

Experience with React (or another modern frontend framework)

Strong backend development experience and API design

Solid understanding of PostgreSQL or other relational databases

Experience with Docker, CI/CD, and cloud infrastructure (AWS, GCP, or Azure)

Strong debugging, analytical, and problem-solving skills

Product mindset with the ability to take ownership from idea to delivery

Comfortable working in a fast-moving startup environment

Experience using AI development tools and modern LLM workflows

Fluent English

Based in Barcelona or willing to relocate

Nice to Have

Startup or founding engineering experience

Experience building AI-powered applications

Knowledge of RAG, vector databases, or multi-agent systems

Enterprise SaaS experience

Interest in aerospace, 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

? Why Join?

Build a category-defining AI platform from an early stage

Work directly with experienced founders and technical leaders

Own meaningful product decisions and features from day one

Solve challenging engineering problems with real-world impact

Competitive salary plus meaningful equity

Join a high-performing team where your work will directly shape the future of the company

? 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

📌 Senior Full-Stack Software Engineer (Barcelona)
🏢 OnHires
📍 Barcelona