Senior Full-Stack Software Engineer
Primary stack
Nice to have's
Job description
About the Position
Senior Full-Stack Software Engineer
📍 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.
Responsibilities
- 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
Requirements
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
© OnHires. This job description was sourced from the employer's public career page. TheJob is not the employer — we index the posting and route candidates to the source. All content rights and hiring decisions belong to the employer.
OnHires was founded in 2021 by Vasyl Grygorovych and Viktoriia Ihnatieva to help companies find and hire the best tech talent the world offers.As business owners, both Victoria and Vasyl were frustrated by how difficult and costly it was to quickly scale development teams. Having lived in multiple countries and traveled to every continent in the world, they realized that great talent could be found anywhere. At the same time, they realized that it’s difficult for both companies and talent to find each other outside of their own geographical location. In an effort to solve this problem, Viktoriia and Vasyl founded OnHires.You can read more about their background here:🚀 Our missionTo connect great companies with even greater talent. We believe that talent can be found anywhere but this is not always the case with opportunities. We are on a mission to bridge that gap and create equal opportunities for everyone. To achieve this, we are building an agency that will help companies unlock global talent.
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