Lead/Senior AI FullStack Software Engineer
Nix
Posted: March 23, 2026
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Quick Summary
As a Lead FullStack Engineer at our European online car market, you will be responsible for shaping the future of online car markets and enhancing user experience for millions of car buyers and sellers.
Required Skills
Job Description
About the client:
Our customer is the European online car market, with over 30 million monthly users and a presence in 18 countries. As a Lead FullStack Engineer, you will play a pivotal role in shaping the future of online car markets and enhancing the user experience for millions of car buyers and sellers.
Responsibilities:
• Continue the evolution and scaling of our freshly released, native ChatGPT apps and custom MCP integrations.
• Develop and maintain high-traffic, public-facing interfaces hosted on AWS modern cloud infrastructure.
• Work heavily with AI agents (Claude Code, ChatGPT/Codex) to maintain and extend a codebase
• Operate with full team autonomy, collaborating closely with the Engineering Manager in a "co-author" environment.
• Follow the "you-build-it-you-own-it" philosophy, taking full responsibility for the SDLC and production readiness.
• Explore and implement emerging AI frameworks and technologies to keep the product at the forefront of the GenAI market.
Requirements:
• 7+ years of experience developing reliable, highly available, and scalable software systems.
• Strong experience working with AI agents (Claude Code, ChatGPT/Codex) to maintain and extend a codebase
• Strong proficiency with backend development using Node.js and TypeScript.
• Deep experience with Model Context Protocols (MCP).
• Proven track record of using AI tooling (ChatGPT, Codex, Claude Code) for rapid operator-driven development.
• Hands-on experience with modern cloud infrastructures, specifically AWS, Terraform, and Docker.
• Strong proficiency with frontend development (HTML, CSS, JavaScript) and component-based SSR frameworks like Next.js or React.
• Experience with SQL and NoSQL datastores, as well as developing in service-based API environments.
• Strong understanding of software architecture, design patterns, and clean code principles.
• A modern, energetic mindset with critical thinking and systemic vision skills, the ability to work independently and take high-level ownership.
• Experience with formal CI/CD pipelines and monitoring services.
• Upper-intermediate English level.
We offer*:
• Flexible working format - remote, office-based or flexible
• A competitive salary and good compensation package
• Personalized career growth
• Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more)
• Active tech communities with regular knowledge sharing
• Education reimbursement
• Memorable anniversary presents
• Corporate events and team buildings
• Other location-specific benefits
*not applicable for freelancers