Senior Software Engineer (C#)

NMI is seeking an experienced Senior Software Engineer to join our Core Gateway team, responsible for developing and maintaining our primary payment gateway platforms. This team ensures reliable, secure, and scalable transaction processing for merchants worldwide, supporting our mission to push the boundaries of innovation in the payments industry.

In this role, you will design and deliver complex backend systems that power secure, high-performance payment processing. You will take ownership of significant components within the Core Gateway platform, ensuring long-term maintainability and operational excellence. Collaborating closely with cross-functional teams, you will guide project delivery, manage technical risks, and drive improvements in observability and fault tolerance.

The ideal candidate will have a Bachelor's degree in Computer Science or equivalent experience, with a minimum of 5 years developing complex software applications in a commercial environment. Advanced proficiency in C# or PHP is required, along with a strong understanding of object-oriented design principles. Experience with relational databases, cloud environments, and security best practices is essential. Excellent communication skills and the ability to mentor others are also important.

We offer a competitive annual salary of £50,000 - £65,000, along with an annual bonus scheme dependent on individual and company performance. Additional benefits include 25 days holiday, a remote-first culture, and comprehensive health and dental coverage. We are committed to providing a supportive and inclusive work environment that fosters professional growth and development.

At NMI, we value creativity, innovation, and collaboration. Joining our team means being part of a company that is dedicated to enabling more payments in more ways and more places. If you are passionate about developing cutting-edge payment technology and want to make a meaningful impact in the fintech industry, we encourage you to apply.