Senior Software Engineer (Java / Kotlin) - Product Page

About the job: At Allegro, we operate at a massive scale where performance and reliability are paramount. Within the Razor team, we maintain the critical backend infrastructure for the entire checkout and purchase path. Our service acts as the central hub, providing essential offer data to nearly 60 critical services - including Show Product, Listings, and Cart - across mobile, web, and desktop. Operating on nearly 500 instances and handling traffic of up to 50,000 requests per second, this high-throughput environment demands exceptional focus on high availability, Java performance optimization, and scalable architecture. Important things for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost):PLN 18 850 - 25 900Annual bonus based on your annual performance and company results. Long term discretionary incentive plan based on Allegro.eu shares (restricted stock units). Our team is based in Toruń. What You'll Do: Massive Scale: Design, build, and optimize systems that handle thousands of requests per second. This is high-availability, high-performance engineering in practice. Master advanced technologies: Work in a world-class, cloud-native environment (GCP). Our core technologies include Java, Kotlin, Spring, MongoDB, microservices, and Airflow (Big Data). True Ownership & Autonomy: We live by the 'you build it, you run it' philosophy. You'll join an agile, autonomous team with full ownership of your microservices—from design to deployment. Engage with diverse business initiatives: Partner with PMs to analyze requirements and drive numerous business initiatives across Allegro. Drive innovation with LLM: Participate in the development of new tools based on Large Language Models. Work with an experienced team: Benefit from a high-agency environment with support and development opportunities provided by senior experts. As a senior developer, you will also have the opportunity to share your knowledge and mentor colleagues with less experience. Ensure system reliability: Maintain the stability of complex architectures through participation in on-call duty. We are looking for people with: Commercial experience: 5 years of experience in building and maintaining complex, high-scalability systems. Strong technical foundation: Proficiency in Java (primary) and Kotlin, with a focus on reactive programming. Advanced database skills (nice to have): Hands-on experience and advanced knowledge of MongoDB. Business-oriented mindset: Experience in collaborating with Product Managers and analyzing business requirements. Team collaboration skills: A track record of frequent cooperation with other technical teams to deliver shared goals. Reliability and ownership: Readiness to participate in a structured on-call rotation to ensure system stability. What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16' or 14' MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism (see more here), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here.#goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale, which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!