Senior Backend Engineer

O projekcie: We are hiring on behalf of our client, a global innovator in fitness and wellness technology. Their mission is to empower people to live fit, strong, long, and happy lives by delivering integrated experiences to millions of members anytime, anywhere. We are looking for a Senior and Mid Software Engineers to join the Content Cloud team. In this role, you will design and build high-performance backend systems that power content delivery across a global platform. You will act as a technical leader within the team, driving architectural decisions, mentoring engineers, and ensuring the reliability and scalability of systems used by millions of users. This is a hands-on role with strong ownership and impact on distributed, event-driven systems at scale. Salary:- Mid: 21 000 PLN - 23 000 PLN gross on the Contract of Employment- Senior: 23 000 PLN - 30 000 PLN gross on the Contract of EmploymentWhat we offer:- 100% paid medical care- Multisport- Creative tax (KUP)- Home office allowance- MacBook Pro Wymagania: Requirements: Technical Expertise - 6+ years of experience building high-performance, scalable backend systems as Senior/4+ years of experience as a Mid Engineer- Strong proficiency in Kotlin, Python, or similar backend languages- Experience with modern backend frameworks (e.g., Spring Boot or Python-based frameworks)- Strong experience with both relational (PostgreSQL, MySQL) and NoSQL databases (DynamoDB, MongoDB)- Hands-on experience with microservices and event-driven architectures- Experience with distributed streaming platforms such as Kafka- Solid understanding of API design (REST, gRPC, or GraphQL) Cloud & Infrastructure - Hands-on experience with AWS services (e.g., S3, DynamoDB, Lambda, SQS, IAM)- Experience with Docker and Kubernetes- Familiarity with infrastructure and deployment tooling (e.g., Terraform, GitHub Actions, Jenkins)- Experience with caching systems such as Redis or Memcached Engineering Practices - Strong understanding of CI/CD, DevOps, and Agile methodologies- Experience with observability and monitoring tools (e.g., Datadog, Sentry)- Proven experience in production support and incident management in distributed systems Stack: - Kotlin (main codebase)- We're open to: Java/Go/TypeScript/JavaScript,- Other tools: REST/gRPC/GraphQL, Kafka, Redis, PostgreSQL/MySQL, DynamoDB/MongoDB, AWS, Docker, Kubernetes Codzienne zadania: - Design and build high-performance, scalable backend services and APIs supporting global content delivery - Architect event-driven systems and microservices handling large-scale traffic and real-time interactions - Drive system design decisions with a focus on reliability, performance, and security - Lead technical discussions, architecture reviews, and design decisions across teams - Define and promote reusable patterns, components, and engineering standards - Mentor engineers through code reviews, pair programming, and technical guidance - Identify system bottlenecks using monitoring, tracing, and load testing tools - Optimize performance through data modeling, caching strategies, and query improvements - Champion best practices including CI/CD, automated testing, observability, and infrastructure as code - Maintain high standards for code quality, scalability, and maintainability - Continuously improve development processes and system architecture - Partner closely with Product, Design, and QA to deliver impactful features - Translate business requirements into scalable technical solutions - Act as a domain expert within the team and contribute to platform-wide initiatives