Senior Backend Engineer (Node.js / NestJS) – Greenfield Product
Senior Backend Engineer (Node.js / NestJS) – Greenfield Product
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 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.
Your Skills
Must Have
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
Apply To This Job
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 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.
Your Skills
Must Have
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
Apply To This Job