Senior Backend Engineer (m/w/d)

hitecture and you own the tickets. Here you pick the technology, design the architecture, and set the standards the backend runs on. 40,000 buyers, 20+ countries, 130,000 vehicles sold a year through one auction backend, and you decide how it scales. Location: Central Berlin — hybrid, 3 days in the office and 2 days from home.   About us CarOnSale is the AI-powered platform for B2B used car trading in Europe. Over 40,000 buyers from more than 20 countries trade on our platform — and 85% of inventory is exclusive to us. We connect software, pricing intelligence, logistics and financing in one layer — as the operating system for an entire industry. One Platform. One Profit Engine.   Your responsibilities You own backend development end to end: technology selection, architecture design, and implementation of the features that carry platform performance and scaleYou build AI-first. Coding agents, LLMs and AI-assisted development are part of the daily workflow here, not a pilot projectYou set the standards: code quality benchmarks, development practices and CI/CD pipelines, agreed cross-functionally and enforced in reviewYou mentor the engineers around you, what you know, and raise the bar on backend practiceYou challenge how we work. When our approach is wrong, you say so and you bring the better one   What you bring 8+ years in software engineering, 5+ of them focused on backendDeep TypeScript proficiency, with strong Node.js, NestJS and PostgreSQL experienceA proven mentorship track record: you have coached engineers and raised the standard around youSolid command of Git, Docker and CI/CD pipelinesComfortable in Scrum or Kanban, working with JIRA and ConfluenceEnglish at C1 level, written and spoken, for daily work with an international teamAI-native working style: you use AI tools in your own development workflow and have real judgement about where they accelerate you and where they don'tBased in Berlin or ready to relocate Nice to have WebSockets or other real-time systemsSearch frameworks such as Elasticsearch or LuceneAutomotive or B2B trading backgroundConversational German   What to expect from us Hybrid working: 3 days in office, 2 days remote – plus 25 "Work from Anywhere" days per year28 days annual leave2× annual career & development conversationsCompany pension with 20% employer contributionFully paid Deutschlandticket (public transport)FitX membership or Urban Sports Club subsidyVirtual stock options — in the upsideModern IT setup for your day-to-day workStructured onboarding with buddy programme and social eventsLived diversity: active women's network, meditation & prayer room   your CV is enough. Skills: Engineering