CarOnSale

Senior Frontend Engineer – Greenfield Product (Angular) Freelance Contract | 9–12 months Remote from Brazil About the Project Castle Tech GmbH is building a new standalone product from the ground up and is looking for an experienced Senior Frontend Engineer (Angular) to join us on a freelance basis for 9–12 months. This is a high-impact engagement where you will influence system design, architecture, and product direction from day one. You will work closely with product and engineering to turn ideas into production-ready software while setting the foundation for how the system evolves. If you enjoy building products from scratch, designing clean architectures, and taking ownership of meaningful projects, this contract will allow you to make a real impact. What You'll Work On - Build a new production-grade product from the ground up - Design and implement a scalable frontend architecture using Angular and TypeScript - Take ownership of features from concept to deployment - Collaborate closely with product managers, designers, and backend engineers - Contribute to technical architecture and system design decisions - Help establish development standards, CI/CD pipelines, and engineering best practices - Mentor other engineers through code reviews and technical feedback - Continuously improve development workflows using modern tools and AI-assisted engineering AI-Augmented Engineering AI is part of how we work. We expect engineers to actively use modern AI tooling to improve productivity and quality. You should be comfortable: - Using AI-assisted development tools in your daily workflow - Writing effective prompts and evaluating AI-generated output critically - Identifying AI limitations and failure modes - Exploring modern AI workflows and tools This is not about blindly accepting AI suggestions — it's about using AI thoughtfully to work smarter and build better systems. Your Skills Must Have - 5+ years of experience as a frontend engineer - Strong expertise with Angular (v11+) and TypeScript - Experience designing scalable frontend architectures - Strong understanding of software design principles and maintainable systems - Experience with modern frontend tooling (NPM, Webpack or esbuild) - Experience working with Git, CI/CD pipelines, and Docker - Experience working in agile teams (Scrum or Kanban) - Strong communication skills in English (written and verbal) - Availability for 9–12 months, starting as soon as possible - Comfortable working remotely with European time zone overlap (able to attend meetings during CET/CEST business hours) Nice to Have - Experience with frontend testing frameworks (Jest, Cypress, Playwright) - Experience building greenfield products or new platforms - Familiarity with AI-related components such as RAG or vector databases - Experience with Material Design or product-oriented UI development - Conversational German - Previous experience working with European clients or distributed teams What You'll Own As a Senior Engineer, you will play an important role in shaping both the technology and the team. You will: - Design systems with clear component boundaries and scalability in mind - Identify technical risks and propose practical solutions - Help improve the team's engineering standards and productivity - Mentor other engineers and contribute to technical decision-making - Deliver high-impact features that support business and product goals Contract Details - Duration: 9–12 months (with potential for extension) - Location: Remote from Brazil - Start date: ASAP - Engagement type: Freelance / Contract (B2B or international contractor agreement) - Work arrangement: Fully remote with expected overlap during European business hours (CET/CEST) - Time zone: Flexible, with core collaboration hours aligned to Central European Time Why Work With Castle Tech? - Build something new – work on a greenfield product from the start - Real technical ownership – influence architecture and system design - Modern engineering environment – use the latest tools and workflows - Collaborative team – work with experienced engineers, product managers, and designers - Remote-first mindset – async-friendly culture with clear communication practices - International exposure – work with a European tech company from Brazil

Role Description Castle Tech GmbH is building a new standalone product from the ground up and is looking for an experienced Senior Backend Engineer (Node.js / NestJS) to join us on a freelance basis for 9–12 months. In this role, you will play a key role in shaping the product's architecture, backend services, and technical direction. You will work closely with frontend engineers, product managers, and stakeholders to turn ideas into reliable, scalable backend systems. This is an opportunity for engineers who enjoy designing systems, solving complex technical challenges, and taking ownership of meaningful projects from concept to production. What You'll Work On - Build and maintain scalable backend services using Node.js and NestJS - Design a clean system architecture for a new production product - Take ownership of features from concept through deployment - Define and implement APIs, services, and backend infrastructure - Collaborate with frontend engineers, product managers, and designers - Establish development standards, CI/CD pipelines, and engineering best practices - Mentor other engineers through code reviews and technical feedback - Continuously improve workflows using modern tooling and AI-assisted engineering AI-Augmented Engineering AI is part of how we work. We expect engineers to actively use modern AI tools to improve development speed and quality, while maintaining strong engineering judgment. You should be comfortable: - Using AI-assisted coding tools in your daily workflow - Writing effective prompts and critically evaluating AI output - Identifying AI limitations and failure modes - Exploring modern AI-driven development workflows This role is for engineers who see AI as a tool to enhance engineering, not replace good engineering practices. Qualifications - 5+ years of backend engineering experience - Strong experience with TypeScript, Node.js, and NestJS - Experience designing scalable backend architectures - Strong understanding of software design principles and maintainable systems - Experience with relational databases (PostgreSQL or similar) - Experience working with Git, CI/CD pipelines, and Docker - Experience mentoring or supporting other engineers - Experience working in agile teams (Scrum or Kanban) - Strong communication skills in English (written and verbal) - Availability for 9–12 months, starting as soon as possible - Comfortable working remotely with European time zone overlap (able to attend meetings during CET/CEST business hours) Nice to Have - Experience with microservices or event-driven architectures - Experience building greenfield or standalone products - Familiarity with AI-related components such as RAG or vector databases - Experience integrating AI services or data-driven systems - Conversational German - Previous experience working with European clients or distributed teams What You'll Own As a Senior Engineer, you will play a key role in shaping both the technology and engineering culture. You will: - Design backend systems with clear service boundaries and scalability in mind - Identify technical risks early and propose effective solutions - Contribute to architecture discussions and system design - Improve the team's engineering standards and productivity - Mentor engineers and contribute to technical decision-making - Deliver high-impact backend features aligned with product and business goals Contract Details - Duration: 9–12 months (with potential for extension) - Location: Remote from Brazil - Start date: ASAP - Engagement type: Freelance / Contract (B2B or international contractor agreement) - Work arrangement: Fully remote with expected overlap during European business hours (CET/CEST) - Time zone: Flexible, with core collaboration hours aligned to Central European Time Why Work With Castle Tech? - Build something new – work on a greenfield product from the start - Real technical ownership – influence architecture and system design - Modern engineering environment – use the latest tools and workflows, including AI-assisted development - Collaborative team – work with experienced engineers, product managers, and designers - Remote-first mindset – async-friendly culture with clear communication practices - International exposure – work with a European tech company from Brazil