AI Full Stack Engineer | AI-Assisted Development in Madrid

AI Full Stack Engineer | AI-Assisted Development

Remote in Europe | B2B contract | €70,000–€85,000 annual contract value

Our client is seeking a hands-on AI Full Stack Engineer. In this role, you will help build a new SaaS ledger platform for an international fintech business. This is a hands-on role where you’ll take requirements through design, development, testing, deployment and production support.

You’ll use AI coding tools as part of your everyday workflow, while taking full responsibility for the quality, security and behaviour of the software you deliver.

What you’ll do

• Build backend services, APIs and integrations using Node.js and TypeScript.
• Design PostgreSQL data structures and optimise queries and data flows.
• Develop frontend functionality using React and TypeScript.
• Build secure, scalable features for a multi-tenant SaaS platform.
• Work with AWS, CI/CD pipelines and cloud-native deployment practices.
• Use tools such as Cursor, Claude Code or GitHub Copilot to support development, testing, debugging and refactoring.
• Review and validate AI-generated code before it reaches production.
• Solve technical and production issues, contribute to architecture decisions and review code.

What you’ll bring

• Senior-level, hands-on software engineering experience with Node.js, TypeScript and PostgreSQL.
• Strong practical experience using AI coding tools or agents across the development lifecycle. You can give them useful context, spot mistakes and security risks, and improve their output.
• Experience delivering features from initial requirements through to production support.
• Experience with SaaS or multi-tenant systems, AWS, APIs, security and CI/CD.
• Frontend experience, ideally with React and TypeScript.
• The ability to work independently in an existing codebase and explain your technical decisions.
• Good written and spoken English.

Experience with Kubernetes, event-driven systems, fintech, payments or ledger platforms would be useful. Russian language skills would also be an advantage.