Fintech Qa Engineer: Wallet, Card Issuance & Api Testing

Foodstuffs; Auckland; On-site; NZD 100,000 - 140,000; Full time

Job summary

Crossware in Auckland is seeking a Senior Backend Developer to join our team in Auckland, working from the Crossware office, 40 hours per week. This hands-on role focuses on designing, building, and maintaining scalable backend systems used in production environments serving thousands of customers.

You will work in C# and .NET, develop RESTful APIs, contribute to architecture decisions, and ensure performance and reliability.

Qualifications

• 3 years of relevant work experience with C# and .NET.
• Strong API design and distributed systems knowledge.
• Experience with Azure and data modelling (SQL/NoSQL).
• Familiarity with Docker and Kubernetes in production.

Responsibilities

• Design, build, and maintain backend services using C# and .NET.
• Develop and maintain APIs (RESTful and/or event-driven).
• Contribute to system architecture and technical design decisions.
• Ensure high performance, scalability, and reliability of production systems.
• Debug and resolve complex issues across backend, frontend, and cloud environments.
• Work with and incrementally improve legacy systems.
• Collaborate with engineers, product, and support teams to deliver robust solutions.
• Contribute to code quality, testing, and deployment practices.

Skills

C#

NET Core

API design

Distributed systems

Azure

SQL/NoSQL

Docker

Kubernetes

CI/CD

Security

Tools

Git

Job description

Crossware is looking for a Senior Backend Developer to join our team in Auckland, working from the Crossware office, 40 hours per week. This is a hands-on engineering role focused on designing, building, and maintaining scalable backend systems used in real-world production environments, working on systems that serve thousands of customers, where performance, reliability, and maintainability matter. This is not a greenfield-only role, you'll be improving and evolving existing systems while helping shape future architecture.

What You'll Do:

• Design, build, and maintain backend services using C# and .NET
• Develop and maintain APIs (RESTful and/or event-driven)
• Contribute to system architecture and technical design decisions
• Ensure high performance, scalability, and reliability of production systems
• Debug and resolve complex issues across backend, frontend, and cloud environments
• Work with and incrementally improve legacy systems
• Collaborate with engineers, product, and support teams to deliver robust solutions
• Contribute to code quality, testing, and deployment practices

What We're Looking For:

Core Technical Skills
3 Years relevant work experience in the following:

• Strong experience with C# and .NET (Core/Framework)
• Solid understanding of API design and distributed systems
• Experience with cloud platforms (Azure preferred)
• Knowledge of databases (SQL and/or NoSQL) and data modelling
• Familiarity with system design, scalability, and performance optimisation
• Experience with version control (Git) and CI/CD pipelines
• Understanding of security, authentication, and best practices in backend systems
• Experience working with legacy systems and modernisation efforts (e.g. Visual Basic)
• Solid functional understanding of Azure Kubernetes Services (AKS) and Docker containers.
• You understand what it means to run software in production at scale
• You take ownership, not just of features, but of system stability and reliability
• You are comfortable debugging real-world issues across multiple layers
• You are pragmatic and able to work with existing systems, improving them over time
• You care about writing maintainable, well-structured code
• You can use AI tools effectively, while applying judgement, validating outputs, and maintaining engineering standards

Nice to Have

• Experience with Microsoft 365 technologies (Exchange, Graph API, Teams, Outlook)
• Exposure to messaging systems, background processing, or event-driven architectures

How We Work

We don't expect you to know everything. What matters is your willingness to learn, adapt, and grow beyond your current focus. You'll be supported by a team that values practical problem-solving, ownership, and continuous improvement.