Senior Full Stack Product Engineer

At Marsello, we're building the Loyalty Marketing Platform that helps retailers and hospitality brands grow loyal customers wherever they are. More than 2,000 brands around the world use Marsello to deliver personalised marketing, loyalty and customer engagement experiences that drive measurable results.

We're looking for two Senior Full Stack Product Engineers to help shape the future of our platform and the systems that power it.

This is a senior technical leadership role where you'll own significant areas of the product end-to-end, drive architecture and infrastructure decisions, and set the technical standard for how our team designs and builds software.

How we work
We care about engineers who can reason about systems, not just ship features. Success here is measured by the quality and durability of what you build — how well you frame problems, design for scale and reliability, and lift the technical bar for everyone around you.

Our team works across the full stack with a strong backend and platform focus, and we use modern tooling — including AI-assisted development — to move quickly without compromising on engineering rigour. What matters most is sound technical judgement: knowing how systems fit together, where they'll break, and how to build them so they don't.

What you'll do
You'll lead the delivery of complex product initiatives while raising the technical capability of the wider team.

You'll:

• Own technical direction and architecture for major areas of the platform.
• Design robust, scalable backend systems and APIs across our .NET and MongoDB stack.
• Contribute to architecture, infrastructure and engineering strategy alongside others in the engineering team.
• Design and deliver features end-to-end across .NET, MongoDB, React and AWS.
• Make sound trade-offs on data modelling, performance, reliability and maintainability.
• Contribute to infrastructure, observability and platform improvements across our AWS environment.
• Take part in our engineering support rotation and help solve complex customer issues.
• Mentor intermediate and junior engineers through pairing, coaching and technical guidance.
• Use modern development tooling, including AI coding agents, to work efficiently while keeping quality high.

What we're looking for

• Strong software development experience in a SaaS environment.
• Deep experience designing, building and owning backend systems end-to-end.
• Deep expertise with C#, .NET, Web APIs and MongoDB, plus solid React/TypeScript on the front end.
• Strong architectural and system-design skills, with good instincts for scale, performance and reliability.
• Hands-on experience with AWS and confidence working with Terraform.
• Solid understanding of CI/CD, observability and operating production systems.
• Excellent communication skills and the ability to work effectively across engineering, product and customer-facing teams.
• A collaborative mindset and a genuine desire to help others grow.
• Comfort using AI-assisted development tools as part of a modern workflow.

Why Marsello?
You'll join a high-performing, globally distributed team with a strong culture, meaningful product challenges, and real ownership over the architecture and systems that power our platform.
We're open to candidates based anywhere in New Zealand. Wellington is preferred, but not required, as we find occasional face-to-face collaboration valuable for a role that works closely across teams and disciplines.

We also offer:

• Southern Cross healthcare.
• A day off for your birthday.
• A friendly, hard-working culture.
• A supportive growth environment.

If you're excited by building great software, designing systems that scale, and solving complex technical problems, we'd love to hear from you.