Senior Software Engineer - C# (4011) in Manchester

About GBG

Enabling safe and rewarding digital lives for genuine people, everywhere. We make it our mission to ensure more genuine people have digital access to opportunities, and businesses have access to more genuine people. Our technology draws on diverse and reliable data to create a single point of truth for identity and address verification. With over 30 years of experience behind us, our team and technology are focused on enabling safe and rewarding digital lives for everyone. Regardless of age, location or background, genuine people everywhere should be able to digitally prove who they are and where they live.

About the team and role

Documents & Biometrics - Sentinel Product Team. We’re a close-knit group with a high sense of ownership and a shared determination to get things done and keep our customers satisfied. We value every team member's contribution, hold ourselves accountable for quality, and take pride in delivering software that works reliably in the real world.

You’ll be joining the Windows Desktop SDK team within GBG’s Documents & Biometrics product group. The core engineering team consists of three Software Engineers (+ this role) and two QA Engineers, working closely with a hands-on Engineering Manager and a Product Owner. The team is primarily based in Manchester, New Hampshire, with colleagues working remotely from Mexico and California, giving the team a genuinely international feel. This role is hybrid, with an expectation of two days per week in our Manchester, NH office to maximise in-person collaboration with the core team.

Beyond the immediate team, you’ll collaborate with the wider family of squads working across the Documents & Biometrics portfolio, so there’s genuine breadth of exposure and cross-team connection, not just a narrow lane.

Our flagship product is Sentinel, a forensic document-authentication engine trusted by organisations in some of the most demanding identity verification environments in the world, including border control, law enforcement, and regulated financial services. The stakes are high; accepting a fraudulent identity document in these contexts can have serious real-world consequences, and Sentinel exists to prevent that.

Formed in July 2024, this team was brought together with a clear mandate to take ownership of Sentinel and elevate it. That means balancing meaningful feature delivery against a deliberate programme of technical improvement, modernisation, and automation, and there’s a strong roadmap with plenty to get your teeth into. You’d be joining at an exciting point in that journey.

As a Senior Software Engineer, you’ll take ownership of complex features and improvements across the Windows-deployed SDKs and supporting desktop components that power Sentinel. Our software runs across a range of scanning devices, including hardware we badge under our own product lines, and a key part of the role is ensuring robust compatibility is maintained across that device ecosystem. You won’t need to be a hardware engineer; we have dedicated hardware technicians for that. But you will need a practical appreciation for software-hardware interaction and the discipline to test and validate across multiple device configurations.

What you will do

• This is a role with real breadth. You’ll ship features, improve the codebase, and raise the technical bar for the team, often all at once.
• Design, implement, and maintain complex features and fixes in C#/.NET Windows SDKs and supporting desktop components.
• Own technical solutions end-to-end, from design through implementation, testing, and release.
• Improve architecture, code quality, performance, and diagnosability for Windows SDK deliverables.
• Refactor and modernise existing code to improve testability and long-term sustainability.
• Debug and resolve complex Windows issues using logs, runtime behaviour, and deep system analysis.
• Build and evolve automation including unit and integration tests.
• Contribute across the delivery pipeline where needed, covering build automation, packaging, deployment, and validation workflows.
• Maintain compatibility across the range of scanning devices and hardware platforms our software supports.
• Produce and maintain clear technical documentation to support knowledge sharing and onboarding.
• Experiment with and integrate AI tools into the team’s daily workflows to accelerate delivery and quality.
• Collaborate closely with engineers across the Desktop team and wider Documents & Biometrics group.
• Contribute actively to agile ceremonies including sprint planning, stand-ups, and retrospectives.

Skills we’re looking for

• Strong professional experience developing Windows-delivered SDKs and/or desktop components using C# and .NET Framework.
• Proven track record of owning and delivering complex features in production codebases.
• Strong software design, debugging, and problem-solving skills.
• Proficiency with Git/GitHub and collaborative development workflows.
• Experience modernising older codebases to current technologies and standards.
• Experience improving testability, reliability, and automation in Windows-based products.
• Comfortable contributing across the delivery pipeline when needed, covering build, packaging, deployment, and validation.

Desirable Skills

• Document imaging fundamentals for scanning and OCR.
• Proven use of AI tools embedded systematically into day-to-day development, using them to improve quality, accelerate delivery, or reduce toil, not just as an occasional aid.
• C++ experience.
• AWS experience (used for development team infrastructure).
• Experience working with device SDKs, peripherals, or scanner hardware.
• Familiarity with CI/CD systems for Windows builds and validation.
• InstallShield experience, particularly building and maintaining Windows SDK installers.

To find out more

As an equal opportunity employer, we are dedicated to creating a diverse and inclusive workplace where everyone feels valued and empowered. Please inform your GBG Talent Attraction Partner if you require any reasonable adjustments to the interview process.

To chat to the Talent Attraction team and find out more about our benefits and why we’re a great place to work, drop an email to the Talent Attraction team and we’ll be in touch. You can also find out more about careers at GBG and check out our current opportunities.

Unleash your potential and be part of our mission to power safe and rewarding digital lives.