Senior Backend Engineer

Talon.One

ABOUT TALON.ONE:   Talon.One is the most powerful incentives engine that unifies loyalty, promotions and gamification into one holistic platform. Backed by enterprise-grade security and scalability, Talon.One empowers companies to build personalized, profitable promotions and loyalty programs using any data. Today, over 250 of the world’s most-loved brands including Adidas, Sephora and Carlsberg work with Talon.One to drive deeper engagement and lasting loyalty with their customers.   ABOUT THE TEAM: Our development team consists of specialists in frontend, backend, QA, product, and visual design. We work in small cross-functional teams that give everybody insight and hands-on experience of what everyone else is doing. Each team is self-sustained, autonomous, and responsible for a specific feature or area in our platform. We believe in strong collaboration, open communication, and mentoring to allow bi-directional growth. We are working to make Talon.One an inclusive workplace because we believe it is the right thing to do and because we want to have a positive impact on the entire tech industry. We are currently looking for a Senior Backend Engineer to join our development teams. You will work closely with our product people to design the right solutions to our challenging problems while collaborating, mentoring, and supporting the other team members. For this position, we need professionals who are already based in Berlin or willing to move to Berlin.   ONCE YOU ARE HERE YOU WILL: * Lead and deliver features of any size — independently or by coordinating effort across the squad * Drive technical discovery and solution design in collaboration with your PM and Tech Lead * Actively share technical knowledge across the Backend Guild — through discussions, documentation, and knowledge-sharing sessions * Participate in cross-squad (Backend Guild) brainstorming sessions and problem-solving discussions * Mentor and unblock junior and mid-level engineers through pairing, code review, and deliberate feedback * Champion improvements to quality, maintainability, and engineering process within your squad and beyond * Be a crucial member in a small cross-functional team (a squad) * Contribute effectively during all Scrum rituals, facilitation of process maturity increments, and engineering best practices initiatives * Regularly participate in code reviews and provide constructive feedback * Consistently monitor the maintenance of quality standards and proactively recommend engineering or process improvements   WHAT WE NEED YOU TO BRING TO THE TABLE: * 6+ years of experience as a Backend Developer building enterprise-grade web applications — Go strongly preferred, but we're also open to strong backgrounds in other mainstream backend languages (e.g., Node.js, Java, C#, Python). * Basic working familiarity with Go — you don't need deep expertise, but you should be comfortable reading Go code and understanding its core syntax and idioms. * If your background is primarily in another stack: during interviews, you'll need to demonstrate you can pick up Go quickly and show a genuine willingness to build your career in Go — our backend stack (Go) isn't changing, so this is a hard requirement, not a nice-to-have. * Strong architectural instincts — you understand tradeoffs and can articulate them clearly to technical and non-technical stakeholders * The ability to mentor others without being asked — you notice where people are stuck and act on it * A guild mindset: you contribute to backend-wide discussions, not just your squad's backlog * In-depth knowledge of REST API design, PostgreSQL, and Testing Techniques * Experience building scalable, maintainable, and performant large-scale applications * A proven track record of designing the architecture of multiple applications or complex features end-to-end * Hands-on experience owning maintenance, performance, and security concerns for production systems * Strong tendency towards implementing modern best practices like pair-programming sessions, unit and integration tests, adaptation of AI and automation, refactoring, SOLID principles, security best practices, documentation as code, regular knowledge sharing, etc. * Big-picture thinking; You collaborate with non-developers to clarify requirements and help plan projects, with an eye on the overall impact on the business & product * A willingness to learn about and contribute to the whole stack is essential * A team-first attitude; As a group, we strive to leave egos at home * Empathy for your customers and your colleagues   ABOUT TECHNOLOGY:  * Kubernetes running on Google Cloud * PostgreSQL * We use Go for our API, core logic, and internal tooling * TypeScript, React, Redux, and CSS modules for our web application * Cypress for automated end-to-end testing * Other odds & ends in JavaScript and shell script   WHAT'S IN IT FOR YOU: * A Research and Development Department of 90+ of engineers, product managers and product designers in Berlin * Leaders with 8+ years of experience building our promotions engine  * €1,000 annual learning budget and free German language courses to boost your skills * 30 days of annual leave, plus extra paid days for your birthday and moving day * Home office setup budget, a monthly home office allowance * Freedom to work from abroad for up to 90 days worldwide! * Mental health support with nilo.health and a discounted Urban Sports Club membership * 20% company subsidy on your pension contributions * Subsidised BVG public transport ticket and a dog-friendly Berlin office where your furry friend is welcome * Lease your ideal bike through BusinessBike

Sumup

About the team SumUp’s Point-of-Sale (POS) solution empowers cafes, shops, bars, hair salons, and other businesses to operate efficiently and grow. It offers a wide range of features, including product catalogs, inventory management, business analytics, compliance support, and loyalty tools. Our Fiscalization team will accelerate making the following countries fiscally compliant: Italy, Sweden, Norway, Belgium, Austria, and many other European countries. They will also start building the path for integrating with third parties and fiscalizing receipts. As a Senior Backend Engineer, you’ll collaborate with a dynamic, cross-functional team of Product Managers, Product Designers, Engineering Managers, and fellow engineers. About the role You will be working on secure backend systems to ensure our SumUp’s Point of Sale (POS) products are compliant in the different countries in our roadmap. Furthermore, you will work with the Fiscalization squad to understand the challenge in each market to design a unique solution to delivery. You’re a developer who values user-centric design, precision, and seamless collaboration. You bring structure to communication and thrive in a cross-functional environment.  This is also an onsite role based in Berlin. What you’ll do * Build and maintain fiscal compliance solutions to enable 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 systems. * Navigate SumUp's complex POS ecosystem and master fiscalization frameworks across multiple jurisdictions. * Collaborate with distributed squad members and stakeholders across 5+ cities in a hybrid environment. You’ll thrive in this role if: * You have 5+ years experience in backend engineering with Java and/or Kotlin. * You have a strong understanding of fundamental system architecture, design principles, data modeling, and API design. * You have a strong experience with distributed and fault-tolerant systems. * You have user-level experience working with AWS and Kubernetes. * You have good knowledge of Kafka & Postgres & CQRS. Why you should join SumUp * A dedicated annual Learning & Development budget for attending conferences and/or advancing your career through further education * Enrollment onto our virtual stock ownership program - you will own a stake in SumUp’s future success * A corporate pension scheme * 28 days paid leave + 1 for birthday * You’ll attend global offsites and/or hackathons. * You'd enjoy other great benefits such as Urban Sports Club subsidy, Kita placement assistance, subsidized office lunches and other location-tailored benefits, Babbel language platform subscription and more! Job Application Tip We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.

Sumup

At SumUp, the Global Bank team builds the core infrastructure and services that give merchants a digital bank account, helping small businesses manage their money easily and reliably.  The Balance Management Squad sits at the core of the Global Bank Platform. Right now, our team is completing a major milestone: consolidating and modernizing our balance management system in Europe. The next big step is creating a global transaction history service; a single, shared platform used by all regions to give merchants consistent and transparent views of their financial activity. As a (Senior) Backend Engineer, you’ll help modernize existing systems while balancing innovation with stability, collaborate with teams across regions, and build reliable services that manage diverse markets with different regulations. If you enjoy solving complex problems on high-load systems, are curious about banking, and are looking for a team that tackles challenges head-on, we’d love to hear from you. What You’ll Do * Build and evolve the SumUp’s core banking services that powers ledger operations and transactions, transforming our regional systems into a unified, scalable global platform. * Tackle complex distributed systems challenges, ensuring resilient services that continue to perform under high transaction volumes. * Support modernization initiatives by improving observability, adding test coverage, refactoring code for long-term maintainability, and gradually introducing new architectural patterns without disrupting live banking operations. * Contribute to key architectural decisions - build ledger and transaction history systems from the ground up, ensuring a globally scalable banking solution for our clients. * Collaborate with teams across Risk, Treasury, Finance, and Infrastructure to ensure smooth, compliant, and reliable global operations * Take ownership from design to production, running the services you build, monitoring their performance, and continuously improving how we deliver high-quality software at scale. You’ll be great for this role if * You have solid backend experience building reliable, high-volume services and you think carefully about system design, APIs, data modeling, and how services interact. * You are proficient in Golang and comfortable learning and working with other languages as needed, e.g. Kotlin or Elixir. * You write maintainable, well-tested code, follow CI/CD best practices, and take responsibility for the software you build from development to production. * You’re comfortable building, deploying, and running services in cloud environments like AWS using Docker and Kubernetes. * You’re eager to learn about relational databases that perform well under load and maintain data consistency. * You are a collaborator who enjoys working across regions, communicating clearly, exchanging feedback effectively, and making thoughtful technical decisions together. * You have a curiosity for building reliable financial services and banking domain It’s a plus if you have * Knowledge of Elixir - some of our legacy services are written in Elixir, and while it's not essential, it would be useful if you've worked with it before * Deeper PostgreSQL experience - we rely heavily on Postgres, so if you've done performance tuning, complex queries, or schema design, that's a plus * Experience with event streaming platforms (Kafka preferred) and modern observability stacks (Grafana, Honeycomb, etc.) Why you should join SumUp * Be part of a company that values diversity and celebrates unique perspectives. * Work with a global team of skilled professionals in an environment that fosters collaboration, learning, and growth. * Be part of a global tribe building a banking solution from the ground up and delivering impactful solutions to the real-life problems of millions of SumUp merchants all over the world * Career growth and learning opportunities: We invest in your development through regular training, mentorship programs, SumUp University leadership cohort and a yearly learning budget (2,000 EUR) * Sabbatical program for tenured SumUppers * Join a global team where you belong: Check out our D&I Initiatives and Employee Resource Groups such as Pride Club, SumAfro, Neurodiversity, Grupos Mais, Women in Tech, and more * Health & wellness benefits: in-house fitness classes, gym in the office, subsidized Urban Sports Club and available psychotherapy sessions * A lot of other benefits such as Subsidized Public Transport Card, Kita placement assistance, Pension Scheme, Language Learning platform/courses etc. * Enrollment onto our virtual stock ownership program - you will own a stake in SumUp’s future success About SumUp Be empowered to do more that matters. At SumUp, we're on a mission to empower small businesses across the globe by providing a vast set of simple and affordable business tools to help them start, run, and grow their businesses. Today, over 4 million businesses in 36 markets rely on SumUp as their financial partner to manage payments, finance and customer relationships. Our commitment to small businesses is reflected in our diverse team of over 3,000 SumUppers from over 90 nationalities, united by global collaboration and an innovative mindset. Our core values lay the foundation for who we are and what we stand for, shaping our work culture and driving our success. We foster an inclusivity and continuous learning culture, providing a safe space for personal and professional growth. Our differences make us unique and strong as we strive to create an environment where everyone belongs and feels supported, no matter how they identify. SumUp is proud to be an Equal Employment Opportunity employer, actively seeking and embracing diversity in our workforce. We don't make hiring or employment decisions based on race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. Our commitment extends beyond recruitment to creating a safe and respectful workplace where harassment of any form is strictly prohibited. Explore career opportunities with us and join a team driven by collaboration, innovation, and a shared vision of creating a world where everyone can build a thriving business. Discover more about our vibrant and inclusive work culture and how we work on our careers website, and follow our journey on LinkedIn and Instagram. Job Application Tip We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.