Senior Software Engineer .NET C#

At Rydoo, we make expense management simple, so people can focus on the important work, not their receipts. More than one million users trust us to submit, approve, and control expenses faster and smarter. Semine shares that same mission. Since 2015, the team has been building AI technology that removes the repetitive, time-consuming parts of accounting, helping finance teams work smarter. In July 2025, Semine joined forces with Rydoo to shape the future of financial automation. Together, we’re creating a complete, AI-powered platform that simplifies accounts payable and expense management, helping businesses run simpler, faster and smarter financial operations. We’re a global team of +200 people who believe great tech should make life easier. If you have big ideas and want to build something that actually helps people, you’ll fit right in. Rydoo / Semine in a snapshot Ambitious international team 33 nationalities speaking over 15 languages 240+ employees across multiple countries Easy-to-use spend management app available on iPhone and Android Supporting over 10,000+ clients and 1 million+ users worldwide 4.6 employer score on Glassdoor Hybrid work policy The Role At Rydoo / Semine, we build smart, simple solutions that help people spend less time on expenses and more on what matters. As a Senior Software Engineer, you will: Work in one of our squads, a cross-functional, autonomous team. Shape the core of our product - designing and extending systems that make expense management faster and smarter for thousands of users worldwide. Bring valuable features into production and follow up on their performance and maintenance. Contribute on front-end features. Design and implement REST APIs. Help architect several of our microservices. Design and write automated tests. Setup infrastructure and pipelines via Infrastructure as Code (IaC). Several years of experience with backend development. Excellent knowledge of .NET, C#. Good knowledge of Entity Framework (or any ORM like NHibernate), SQL Server or similar. A team player with a passion for writing clean and testable code within a cross-functional team. Experience in optimising the performance and scalability of applications to support our ever-growing user base. Experience with Service Oriented Architecture using Service Bus to connect everything is a plus. Knowledge of Azure Cloud (or AWS, GCP) is a plus. Some experience with Angular is a plus, but having the curiosity and willingness to learn front-end technologies is also much appreciated. Agile and DevOps experience is a plus. Experience with LLMs is a plus. Ability to stay up-to-date with industry trends, best practices, and emerging technologies to continuously improve our development processes and drive innovation. A degree in computer sciences or a related field is preferred, but any equivalent experience is just as valuable. Next to our amazing team, informal & international company culture and our mission to become the number 1 spend and invoice management platform in Europe, we offer some nice benefits that make working at Rydoo / Semine even more fun: A competitive package, including salary and benefits €1000 / year learning and development budget Rydoo Hybrid Work Policy: flexibility to work from home while also fostering team collaboration in our Warsaw hub 1x a week. Rydoo On Tour: our international mobility program that gives employees the possibility to temporarily relocate to one of the countries we have a Rydoo office. Professional freedom and a flexible work environment Upskilling through training and coaching programs Regular company and team events Wonderful international team with more than 33 different nationalities Spectacular onboarding program for all new Rydooer’s Permanent contract Why Join Us At Rydoo / Semine, we celebrate diversity and are committed to creating an inclusive environment for all employees. We value and encourage ongoing learning opportunities and career progression. Even if you don't tick every box but see yourself contributing, we encourage you to apply. We're more interested in finding a well-rounded individual with a can-do attitude. Your passion, dedication and desire to learn are what matter most to us. Check us out LinkedIn: https://www.linkedin.com/company/rydoo Glassdoor: http://bit.ly/2UujjWJ Instagram: https://www.instagram.com/rydoo/ YouTube: https://www.youtube.com/channel/UCTZYj7vm_ZcsGFL18jWHt_A Inside Rydoo Blog: https://www.rydoo.com/inside-rydoo/