Senior Backend Engineer (f/m/x)

You don't want another agency contract where someone else owns the architecture 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: Remote from anywhere in Brazil, freelance contract. Your day starts at 7:00 local time to overlap with the European engineering team. 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. What you own • You own backend development end to end: technology selection, architecture design, and implementation of the features that carry platform performance and scale • You build AI-first. Coding agents, LLMs and AI-assisted development are part of the daily workflow here, not a pilot project • You set the standards: code quality benchmarks, development practices, and CI/CD pipelines, agreed cross-functionally and enforced in review • You mentor the engineers around you, share what you know, and raise the bar on backend practice • You 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 backend • Deep TypeScript proficiency, with strong Node.js, NestJS and PostgreSQL experience • Proven mentorship track record: you have coached engineers and raised the standard around you • Solid command of Git, Docker and CI/CD pipelines • Comfortable in Scrum or Kanban, working with JIRA and Confluence • English at C1 level or above, written and spoken, for daily work with an international team • AI-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't • Available to start your day at 7:00 Brazil local time Nice to have • WebSockets or other real-time systems • Search frameworks such as Elasticsearch or Lucene • Automotive or B2B trading background What you get • Fully remote from anywhere in Brazil, on a freelance contract • Architecture ownership from day one, not after a probation period • An engineering culture where AI tooling is embedded in how the work gets done • Direct access to the European engineering team, not a client-vendor layer in between • Backing behind the platform you build on: founded 2018, 400 people, €70M Series C in July 2025 led by Northzone and HV Capital Apply now — your CV is enough.