Backend Engineer (B2B

About the role

The role owns the design, implementation, and continuous operation of backend services that power the AI operating system for global beauty, wellness and self-care. You will be accountable for translating product and design intent into resilient, scalable, and observable backend features from initial discovery through production rollout and ongoing optimization. This position requires deep technical ownership across the full lifecycle of backend systems, ensuring reliability, performance, and security in a high-velocity environment. You will work alongside a diverse and experienced engineering team, leveraging modern tooling and practices to solve complex problems. The successful candidate will drive momentum by shipping impactful features while maintaining rigorous standards for code quality and system integrity. You will leverage AI tools not as a replacement for engineering judgment but as a force multiplier to accelerate development without compromising depth of technical review. This is an opportunity to shape foundational components of a platform used by millions of consumers and thousands of businesses worldwide.

Key facts

What you'll do

• Collaborate closely with Product, Design, Frontend, Infrastructure, and Mobile engineers to take features from discovery to rollout and beyond.
• Be responsible for features from discovery to observability: technical design, implementation, testing, and rollout.
• Design, build, and maintain efficient, scalable, and reliable Ruby/Elixir code.
• Work with a polyglot stack (Ruby, Elixir, GraphQL, TypeScript, gRPC) and modern messaging systems (Kafka).
• Operate within a Kubernetes-driven environment as we continue moving to a microservice architecture.
• Embrace Domain-Driven Design to build high-quality, impactful products from inception to delivery.
• Write tests and automated checks to ensure correctness and reduce the risk of regressions in production.
• Participate in on-call rotations to support production services and respond to incidents promptly and effectively.
• Contribute to architectural discussions and help define long-term technical direction for backend services.
• Optimize system performance, scalability, and reliability through profiling, monitoring, and iterative improvements.
• Partner with data and analytics teams to instrument features and derive insights that inform product decisions.
• Mentor junior engineers by providing guidance, code reviews, and constructive feedback to elevate the entire team.
• Keep up with industry trends and best practices to continuously evolve the codebase and development processes.
• Work within defined release cycles to plan, deliver, and communicate progress on backend initiatives.

Requirements

• Have a Bachelor's or Master's degree in Computer Science, Information Technology, or a related technical field.
• Demonstrate strong proficiency in Ruby and/or Elixir with a solid understanding of language-specific idioms and ecosystem tools.
• Show experience with building and consuming GraphQL APIs and working with TypeScript for frontend integration.
• Bring proven experience with message-driven architectures using Kafka or similar event streaming platforms.
• Show hands-on experience operating services in Kubernetes and managing containerized deployments.
• Demonstrate solid understanding of Domain-Driven Design principles and how to apply them in real-world systems.
• Bring experience with database design, migrations, and query optimization for relational and NoSQL stores.
• Show ability to write clean, maintainable, and well-tested code with strong attention to security and performance.

Nice to have

• Experience with AI-assisted development tools such as Claude, GitHub Copilot, or Cursor in a professional setting.
• Familiarity with fintech integrations, payments, or compliance-related features in backend systems.
• Contributions to open source projects or public code repositories that demonstrate engineering craftsmanship.
• Experience in a B2B SaaS environment with complex integrations and multi-tenant considerations.
• Background in beauty, wellness, or scheduling domains, or familiarity with related product concepts.

Practical notes

The role is based in Warsaw, Poland, with a requirement to work onsite for 4 days per week. Compensation is offered as a B2B contract with a monthly net range of 25-40 k PLN plus RSUs. The position operates within a fast-paced, autonomous environment where engineers are expected to manage their time and deliverables with minimal supervision. Travel is generally limited to local work within the Warsaw area and standard working hours aligned with the team. There are no specific visa sponsorship details listed for this role. The hiring process will follow the company's standard procedures, and candidates should be prepared for technical interviews and practical assessments relevant to backend development.