Software Engineer for Payment Device SDKs (C# / Java)

  • Full Time
  • Bristol
  • This position has been filled.


What is the role?

We are looking for a talented developer with 2+ years experience with C#, Java or another object-oriented language in a commercial environment.

Your role will be to integrate PIN pads and card readers into Payment Device SDKs for the processing of card based transactions. The team is responsible for the continued advancement of NMI’s Payment Device POS framework solutions including but not limited to: integrations with point-of-sale PIN pads, interfaces for customers, bespoke solutions, storage and processing of transaction data, software security.

About Us

NMI develops the most trusted payment software for mobile, online and in-store that is relied on in 38 countries, 24 hours a day, 365 days a year. With offices in Bristol, Chicago, Los Angeles, Salt Lake City and New York, our payment technology powers millions of customers worldwide, ensuring they can take payments worth billions, securely and reliably. You’ve probably used our software when ordering a burger, paying for parking or booking a train ticket – without realising it!

A great place to work!

At NMI we are proud of our people-first culture, we know that our people are what makes NMI great and they are at the centre of everything that we do. We run Employee Engagement Surveys twice a year and are extremely pleased that our staff say our culture and the people are the best things about working at NMI, and we have to agree!

We have a firm commitment to strengthening the diversity of our workforce, and therefore welcome and encourage applications from all communities and underrepresented groups.

We want people to bring their unique blend of experiences, backgrounds, perspectives and knowledge to NMI, as diversity makes us stronger.

What will I be doing?

You will be using a combination of the data that we receive from integrators, devices and databases, building the correct messages, sending them for processing and managing the response with all associated error conditions. Consideration also has to be given to performance, availability and reliability.


  • Development and support of our point-of-sale frameworks and tools
  • Development and support of internal processes relating to different aspects of payment
  • Development and support of other applications required for the companies procedures
  • Part of the team that assists our Customer Support desk with escalated customer queries and issue resolutio


Do I have what it takes?

Essential skills and experience:

  • 2+ years experience with C#, Java or another object-oriented language in a commercial environment
  • Common development environment such as Visual Studio, IntelliJ, Eclipse etc.
  • Attention to detail in all aspects of development
  • Good communication skills; both written and verbal for dealing with suppliers and project partners
  • Good interpersonal skills

Preferred Skills & Experience

  • An understanding of networking principles and protocols such as sockets, HTTPS, DNS and SSL
  • Understanding of Secure Programming Practices
  • Knowledge of SQL
  • Understanding of cryptography and its application in different areas
  • Version control in a multi-user environment
  • Experience in Continuous Integration systems (e.g. TeamCity)

Do you feel like you have a slightly out of the ordinary career path or history? We are open to all walks of life and very willing to hear your story. Please don’t feel like this should be a barrier to securing a great career at NMI! We appreciate success in all shapes and sizes. Fill in the ‘Additional Info’ on your application to tell us more about your path.


As well as being a part of something exciting everyday, you will also receive the following benefits:

  • Annual salary of £30,000 – £40,000 (dependant on experience)
  • 25 days holiday each year (+ bank holidays + 1 day after each year of service with up to a max. of 30 days)
  • Flexible working hours to suit your lifestyle (employees can start their day between 8am and 10am and finish between 4pm and 6pm)
  • A flexible hybrid working arrangement
  • Family Friendly policies (Enhanced Maternity and Paternity Pay and Shared Parental Leave)
  • Annual Bonus scheme
  • We provide our employees with fantastic career progression opportunities, offering specific courses and the possibility to gain further qualifications.
  • Private health insurance upon successful completion of your probationary period
  • A strong commitment to employee wellbeing including mental health first aiders, yoga sessions and employee assist programme
  • Cycle to Work Scheme (government-backed cycle to work scheme)
  • Workplace pension scheme
  • Perkbox subscription – discounts on gyms, restaurants, high street retailers, cinema tickets etc
  • Bonusly colleague reward scheme
  • Employee referral scheme with generous financial reward