Senior Backend Engineer (B2B - Warsaw)

About the TeamJoin the Sell Online Tribe, a dynamic group that empowers merchants to establish their presence online. We create innovative tools that enable millions of entrepreneurs, from barbers to bakers, to market their products and services effortlessly. Our core focus lies in the Online Store and Bookings products, which form the backbone of SumUp’s ecosystem, allowing merchants to manage appointments, highlight their offerings, and process payments—all from their mobile devices.We are a collaborative, cross-functional team of Product Managers, Designers, and Engineers dedicated to delivering exceptional mobile experiences. As a part of this team, you will play a crucial role in expanding into new sectors, bridging the gap between web and mobile, and making digital selling seamless for small businesses worldwide.About the RoleAs a Senior Backend Engineer, you will be instrumental in enhancing SumUp's major merchant-facing online products within the Bifrost team. You will contribute to the development and scaling of key products such as Payment Links, Virtual Terminal, and Unified Gift Cards, while also working on integration solutions that are vital for numerous other SumUp offerings.We are looking for a developer who prioritizes reliability, teamwork, and continuous growth. Your backend expertise will thrive in a high-impact environment where your contributions directly influence merchant success and team scalability.What You’ll DoEnsure scalability and continuous growth of high-priority online products at SumUpDrive the implementation, development, and integration of Online Checkouts across SumUpEngage actively in planning and review sessions at quarterly and sprint levels, providing constructive feedback and estimationsMonitor existing services, applying necessary fixes to maintain platform reliabilityDevelop new features with maintainable and testable codeEnhance application performance for scalabilityParticipate in code reviews to uphold high coding standardsYou Will Excel in This Role If:You have 5+ years of experience in backend engineering with GolangYou possess a robust understanding of fundamental system architecture, design principles, data modeling, and API designYou have substantial experience with distributed and fault-tolerant systemsYou have a passion for delivering high-quality software solutions

Join Nordsec as a Senior Backend Engineer and be a part of our innovative team in Warsaw. We are seeking a talented engineer experienced in Golang to help us build robust backend systems that power our applications. You will work closely with cross-functional teams to design, implement, and optimize backend services that deliver exceptional user experiences.

SKELAR is a pioneering Ukrainian venture builder dedicated to establishing international tech businesses. We collaborate with co-founders to assemble top-notch teams that excel in global markets.Currently, SKELAR operates a range of businesses across various niches, from EdTech to marketplaces. These companies consistently rank among the top startups and product firms in Ukraine, achieving high rankings in the App Store and creating platforms that millions use daily. Major media outlets like TechCrunch and Wired have featured SKELAR's businesses.We take pride in a robust team of over 1,000 specialists who possess remarkable expertise and ambitious goals. Our people are the most valuable asset of the company, and we strive to build businesses with the best talents available in the market.RiseGuide is an expert-driven microlearning mobile application designed around the principles and examples of exceptional role models. Our users are guided by insights from Andrew Huberman and Simon Sinek to break harmful habits, enhance their social media presence with strategies from Alex Hormozi and MrBeast, and develop charisma inspired by Robert Downey Jr. and Steve Jobs.Key Facts about RiseGuide:Achieved unit economics in just 6 weeks and have been actively scaling since (we had an incredible Q5 and grew fivefold last year).Over 200,000 paid users, with ratings of 4.6/5 on the App Store and 4.4/5 on TrustPilot.A team of over 60 individuals from successful tech businesses and top management programs worldwide.We aim to redefine the self-improvement industry, granting users access to expert knowledge on demand. To achieve this, we are seeking a Software Engineer (Golang) to help develop our product's backend and turn our ambitious goals into tangible achievements.What We Offer:Opportunity to make architectural decisions and build systems from the ground up.Minimal bureaucracy and maximum speed to market. A small team focused on results and rapid deployment.Fast feedback loops — your solutions will immediately impact production and influence hundreds of thousands of users.The chance to join the team early and define your area of responsibility.Pure Tech: modern stack with Zero Legacy.

Join IDT Corporation as a dynamic and experienced Senior DevOps Engineer specializing in Golang. In this role, you will leverage your expertise in AWS, Kubernetes (both public and private cloud), Docker, Hashicorp Vault, and Consul to design, implement, and maintain robust infrastructure and CI/CD pipelines that ensure reliability, scalability, and security across all operations.

Join SKELAR, a pioneering venture builder committed to establishing international tech businesses. We partner with co-founders to assemble strong teams that excel in global markets.Currently, SKELAR manages a diverse portfolio of businesses across various sectors, from EdTech to marketplaces. Our ventures have been recognized as top startups and product companies in Ukraine, featuring prominently in AppStore rankings and creating platforms used by millions. Notable media outlets like TechCrunch and Wired have covered our businesses.We take pride in our robust team of over 1,000 specialists, each possessing exceptional expertise and ambitious goals. Our people are our greatest asset, and we strive to build businesses alongside the best talent available.We are currently seeking a Golang Backend Team Lead for PawChamp, a mobile application and online platform designed for dog owners. PawChamp enables pet parents to train their dogs and learn more about care and training through 24/7 chats with experts, the AI companion Pawchie, and educational materials developed in collaboration with dog trainers. Our aim is to provide personalized daily lessons covering all aspects of dog training, from basic commands to addressing behavioral issues. Our strategic goal is to become the leading player in the global online dog training market, fulfilling all needs of pet parents and their dogs beyond training.In October 2025, we earned the title of Product of the Day on Product Hunt.App Store rating: 4.8Intro video about the product: https://www.youtube.com/watch?v=D3vURwhmufgKey Challenges:Enhancing the backend for our mobile products and the PawChamp web platform.Leading, coordinating, and developing the backend development team.Collaborating with stakeholders.Ensuring high code quality and adherence to best development practices within the team.Interacting with adjacent teams to improve system component interaction and optimize processes.Enhancing code, architecture, services, and development approaches.What We Value:

About Our Team At SumUp, we provide a comprehensive Point-of-Sale (POS) solution designed to empower businesses such as cafes, shops, bars, and salons to streamline operations and foster growth. Our platform encompasses a variety of features including product catalogs, inventory management, business analytics, compliance assistance, and loyalty programs. The Fiscalization team is dedicated to ensuring compliance in countries like Italy, Sweden, Norway, Belgium, and Austria, among others. We are also pioneering the integration with third-party services for fiscalizing receipts. As a Senior Backend Engineer, you will work alongside a vibrant, cross-functional team comprising Product Managers, Designers, Engineering Managers, and fellow engineers. Your Role In this position, you will develop secure backend systems that ensure SumUp's POS products are compliant across various countries on our roadmap. You will collaborate with the Fiscalization squad to devise unique solutions tailored to the challenges in each market. We are looking for a developer who values user-centric design, precision, and seamless collaboration. You will excel in a structured communication environment and thrive in a cross-functional team. This is a B2B role based in Warsaw. Key Responsibilities Design and maintain fiscal compliance solutions to support SumUp's expansion across Italy, Sweden, Norway, Belgium, Austria, and other European markets. Develop integrations with third-party services for receipt fiscalization and regulatory reporting. Navigate SumUp's intricate POS ecosystem and familiarize yourself with fiscalization frameworks across multiple jurisdictions. Work collaboratively with team members and stakeholders distributed across 5+ cities in a hybrid working model. You Will Succeed in This Role If You Have: 5+ years of experience in backend engineering with expertise in Java and/or Kotlin. A solid understanding of system architecture, design principles, data modeling, and API development. Hands-on experience with distributed and fault-tolerant systems. Proficiency in AWS and Kubernetes. Strong knowledge of Kafka, PostgreSQL, and CQRS.

Join HelloFresh in Warsaw as part of our HelloTech organization, a vital segment of our global technology team comprising over 1000 professionals. We are dedicated to developing digital products that enhance the end-to-end food experience, encompassing meal kits, ready-to-eat meals, and even specialty items like pet food and premium meat & seafood. Our technology platforms empower millions of customers with personalized food solutions every month.Our direct-to-consumer subscription model is fueled by cutting-edge technology that optimizes every customer interaction—from engaging applications and personalization algorithms to pricing strategies and supply chain management. Although our brands operate independently to cater to diverse customer needs, they are unified by shared platforms, data, and operational excellence crafted by HelloTech.At HelloTech, we work in autonomous, cross-functional teams that take ownership of specific products and domains. By collaborating with our Warsaw office, you will contribute to scalable, data-driven products used across various markets, leveraging a modern tech stack and working with international teams to continuously enhance how our customers discover, order, and enjoy HelloFresh products now and in the future.

Join Saily, where we simplify staying connected while traveling — no roaming fees, no plastic SIM cards, just high-speed, secure mobile data accessible in over 200 destinations. With millions of satisfied customers and countless travelers using Saily at any time, we are dedicated to enhancing their experience.At Saily, we cultivate an AI-driven Product Engineering culture that empowers our engineers to:Own the product development lifecycle from concept to deployment.Leverage AI Agents to automate repetitive coding tasks, maximizing their productivity.Continuously identify and implement improvements within our processes.Embrace curiosity and encourage knowledge sharing.Focus on delivering a seamless, connected experience for our customers.We prioritize growth, contribution, and impactful work over comfort and hierarchy. At Saily, we provide our talented team members with the autonomy and resources they need to excel.Key ResponsibilitiesEnhance our product by developing and maintaining innovative features.Create functionalities that support multi-dimensional personalization, A/B testing, and data analytics.Maintain a robust and high-quality codebase.Continuously seek opportunities to improve code quality and system performance.Provide mentorship on development best practices and offer technical guidance to peers.Contribute to the overall vision and long-term goals of the team.Conduct research and development as needed.Collaborate within a cross-functional team to ensure clear communication among all members.Work alongside engineering, product, and design experts from other teams.Note: This position requires in-office attendance three times a week.

Join Moss, where we empower finance professionals to automate their workflows and make strategic decisions.Our unique culture is centered around impact and growth, fostering an environment where each team member is encouraged to learn and succeed. Recognized by Sifted’s Rising 100 and LinkedIn's Top Startups, we aim to advance your career while making Moss a lasting success.Our Engineering teams are looking for talented Senior Backend Engineers (f/m/d) to join various teams in Warsaw. Open positions include:Sales EnablementPricing & BillingAcquisitionSpend ManagementActivation & Card SpendIn this role, you will collaborate closely with designers, product managers, and frontend engineers to bring innovative ideas to fruition, ensuring our product provides intuitive and efficient tools for business automation and simplification.

Please note that this opportunity requires relocation to our Milan office.About SatispayAt Satispay, we are on a mission to revolutionize everyday payments, making them simple, equitable, and accessible to everyone. Our vision is to shape the future of money, and we are just getting started. Join our movement that empowers millions, driven by a shared purpose to tackle significant challenges. We thrive on speed, bold thinking, and mutual trust, encouraging each other to challenge the status quo while learning and growing together.If you seek more than just another job and wish to create something impactful alongside a talented team, you’ve come to the right place.Your ResponsibilitiesAs a Senior Backend Software Engineer in the Business Team, you will play a pivotal role in shaping the future of digital welfare payments, managing everything from employer benefits to complex products. You will oversee the end-to-end experience for both employers and employees, ensuring long-term satisfaction. Your responsibilities will include:Drive Multi-Service Solutions: Conduct technical analysis for medium-to-large projects impacting multiple employer domain services. Design highly-available, scalable, secure, and maintainable solutions at the core of welfare offerings.Ensure Technical Quality: Implement robust testing strategies, balancing automation and manual coverage, while monitoring gradual rollouts to ensure precise and reliable welfare distributions.Resolve and Anticipate Blockers: Proactively identify and resolve technical obstacles, fostering knowledge sharing across your organization. Address unique challenges in B2B registration flows and high-volume benefit allocations while ensuring code quality through active reviews.Execution and Ownership: Take full ownership of your projects from inception to completion, delivering features that genuinely meet user needs—from employer signup to the first employee spending their welfare benefits—through seamless and efficient backend integration.

We are seeking an experienced Senior Backend Engineer to become a vital member of our dynamic, cross-functional product teams. This role demands extensive technical expertise, exceptional communication abilities, and a proactive, collaborative approach. The successful candidate will be deeply involved in ongoing client projects and seamlessly integrated into our established workflows.

Join Turnitin as a Senior Fullstack/Backend Software Engineer, where your expertise in backend development, particularly with Java and serverless architectures, will be pivotal. We are seeking engineers who are enthusiastic about creating scalable distributed systems and delivering robust software solutions for our acclaimed educational platform.As an integral member of our shared services team, you'll spearhead the development and enhancement of the core systems supporting both our existing and upcoming applications.Key Responsibilities:Architect, develop, and optimize scalable backend services utilizing Java and serverless technologies (AWS Lambda).Design and implement RESTful APIs and event-driven architectures.Contribute to frontend component development as required.Enhance performance and cost-effectiveness of existing services.Collaborate with cross-functional teams, including Architects, Product Managers, and engineering leads, to deliver innovative solutions.Mentor junior developers and promote best practices.Establish and manage CI/CD pipelines.Maintain high-quality coding standards through peer reviews, automated testing, and compliance with development best practices.Document shared components comprehensively, providing usage guidelines and examples.

Join the forefront of online security technology with the world’s leading VPN provider!Are you a passionate problem-solver eager to make impactful contributions? Become a key player in the team behind Threat Protection Pro, the NordLynx protocol, and the fastest VPN globally—tools designed to restore privacy, security, and user control.Your role? Empower millions to reclaim their online security, privacy, and data integrity.As a Senior Backend Engineer on our Notification Center Team, you’ll be vital in designing and maintaining the microservices that facilitate seamless in-app notification delivery. We take pride in being the backbone of numerous features that depend on these notifications for smooth functionality. Our collaborative spirit drives us to work closely with other teams at Nord to pave the way for a scalable future.Ready to tackle the challenges of scalability, code quality, and service stability? Join our team of skilled engineers dedicated to technical excellence and help shape the future of NordVPN and its associated products!

Join Box as a Senior Backend Software Engineer and be part of a pioneering team that is reshaping the world of Intelligent Content Management. In this role, you will work on high-scale, distributed systems, tackling significant engineering challenges such as performance optimization, auto-scaling microservices, ensuring data integrity during large migrations, and maintaining search indexing accuracy. Your contributions will directly impact thousands of enterprise customers, helping them manage their critical business content effectively. If you're ready to drive innovation in AI-powered content management, we want to hear from you!

About the RoleJoin Logz.io as a Backend Software Engineer and be part of a dynamic team that is reshaping the observability landscape. In this role, you will design and develop robust backend systems that scale effectively, ensuring seamless integration and exceptional performance.Key ResponsibilitiesDevelop and maintain scalable backend services and APIs.Collaborate with cross-functional teams to define, design, and ship new features.Troubleshoot and optimize existing systems for performance and scalability.Participate in code reviews and contribute to team knowledge sharing.

Join the Vanguard of Online Privacy!Are you a passionate problem-solver with a knack for innovation? Become a part of the team that brought you Threat Protection Pro, the NordLynx protocol, and the world’s fastest VPN, empowering users with privacy, security, and control over their digital landscape.Your Contribution: Enable millions of users to reclaim their online security, privacy, and data.Join our Notification Center Team and help shape the future of in-app notifications!As a Senior Backend Engineer, you will be instrumental in developing and maintaining the crucial microservices that ensure seamless in-app notification delivery. Our team is the backbone supporting a wide array of features across various teams that rely on efficient notification systems to operate. We are dedicated to collaborating with different Nord teams to pave the way for our scalable future.Are you prepared to tackle challenges related to scalability, cost efficiency, quality code, and maintenance? Help maintain a stable and functional service that acts as an essential component behind many features of NordVPN, NordPass, and NordLayer. Join our team of skilled engineers striving for technical excellence!

Join our team as a Backend Engineer and contribute to our innovative solutions at NordProtect. We are looking for talented individuals with a passion for technology and a strong background in backend development, specifically using Go. In this role, you will collaborate with cross-functional teams to design, implement, and maintain robust and scalable backend systems.

At Veeam Software, we pride ourselves on being the experts in Data and AI Trust, dedicated to empowering organizations to fully understand, secure, and ensure the resilience of their data and AI systems. Recognized as the market leader in data resilience and security posture management, we are perfectly positioned to navigate the convergence of identity, data, security, and AI risk. With our headquarters in Seattle and a presence in over 30 countries, we protect the operations of more than 550,000 customers globally, who rely on us to keep their businesses running smoothly. Embark on this exciting journey with us as we continue to innovate, learn, and create significant impacts for some of the world’s largest brands.About the RoleJoin us as we lead the charge in Kubernetes Backup and Disaster Recovery. Our Veeam Kasten platform is specifically designed for Kubernetes data management, providing enterprise operations teams with a seamless, scalable, and secure solution for backup, restore, disaster recovery, and application mobility. With our commitment to continuous optimization and enhancement, we are integrating our tools with SaaS services and expanding support for virtual machines hosted in Kubernetes, ensuring that we meet the evolving needs of our customers.

Waymo is pioneering the future of mobility with its cutting-edge autonomous driving technology. Established in 2009 as the Google Self-Driving Car Project, our mission is to become the world’s most trusted driver. Our flagship product, the Waymo Driver—The World’s Most Experienced Driver™—aims to revolutionize access to transportation while drastically reducing road traffic fatalities. The Waymo Driver powers our fully autonomous ride-hailing service and is compatible with various vehicle platforms and applications. With over ten million rider-only trips completed and vast experience from driving over 100 million miles on public roads and extensive simulations across more than 15 U.S. states, we are leading the way in safety and efficiency.The RO Performance team plays a pivotal role in enhancing Waymo's self-driving technology. We are responsible for developing and maintaining the crucial infrastructure needed to process and analyze vast amounts of data from real-world driving logs and simulations.Our systems create essential metrics and dashboards that are vital for monitoring product performance, pinpointing areas for enhancement, and facilitating data-driven decision-making. The insights generated by our team directly impact Waymo's operational strategies, weekly performance evaluations, and, ultimately, the safety and reliability of our autonomous vehicles.In this hybrid role, you will report directly to a Staff Software Engineer.