Senior Backend Engineer (f/m/x)

Senior Backend Engineer at CarOnSale drives end-to-end backend architecture and technology choice for a scalable AI-first trading platform. You own architecture, standards, and performance while mentoring peers and setting the bar for backend practice. You work cross-functionally to ship impactful features that connect software, pricing, logistics and financing. This role offers ownership from day one in a fast-growing European marketplace with a strong AI-enabled workflow.

• 28 days annual leave
• Company pension with 20% employer contribution
• Subsidised Deutschlandticket
• FitX or Urban Sports Club membership subsidy
• Structured onboarding with buddy programme
• AI tooling embedded in work processes

• Own backend development end to end: choose tech, design architecture, implement features affecting platform performance and scale
• Build AI-first capabilities, including coding agents and AI-assisted development as part of daily workflow
• Set and enforce code quality benchmarks, development practices, and CI/CD pipelines across teams
• Mentor engineers, share knowledge, and raise backend practice standards
• Challenge current approaches and advocate better solutions when needed

• 8+ years in software engineering, 5+ years backend focus
• Deep TypeScript proficiency with Node.js, NestJS and PostgreSQL experience
• Proven mentorship track record
• Strong command of Git, Docker and CI/CD pipelines
• Comfort with Scrum or Kanban, JIRA and Confluence
• English C1+ for daily collaboration with international team
• AI-native working style and ability to judiciously use AI tools

• mentoring and coaching
• ability to challenge the status quo
• cross-functional collaboration
• TypeScript
• Node.js
• NestJS