Cape Town - Senior Backend C#/.NET Engineer

What is the role?

Protium is looking for a Cape Town-base Senior Backend C#/.NET Engineer to help us build and ship production APIs, services, integrations, and backend systems using C#, .NET, SQL Server, and Microsoft/Azure technologies.

This is a Cape Town–based hybrid role, with in-person office days typically 2–3× per week at our Claremont office.

As a senior engineer, you will be expected to take ownership of meaningful areas of delivery: understanding requirements, shaping technical approaches, making sensible trade-offs, guiding implementation, supporting other developers, and helping ensure that what we ship is clean, secure, maintainable, and fit for production.

You’ll work on high-quality, API-driven systems where attention to detail matters: clean architecture, maintainability, performance, security, scalability, operational reliability, and long-term supportability.

While this is primarily a backend engineering role, we value senior developers who understand the full delivery picture. That may include frontend integration requirements, client-facing workflows, mobile/backend interaction, deployment considerations, production support, and the broader technical decisions that affect the success of a system.

About Protium

Protium is a security-first software development company based in Claremont, South Africa.
We build robust, scalable, future-proof software with a strong emphasis on engineering standards, clean delivery, practical architecture, and long-term maintainability.

Our work is primarily focused on building high-quality software systems for clients in the financial services sector (but not limited to), where reliability, security, correctness, and clear communication matter.

Working model

• Cape Town based
• Hybrid
• Office meetups: typically 2–3× per week
• Full-time preferred
• Contract-to-perm considered
• Positions available: 2

This is not a fully remote role. You should be based in Cape Town and able to attend regular in-person office days in Claremont.

About you

You are a strong backend engineer who can take ownership of complex work without needing every detail to be prescribed upfront.

You are comfortable moving between technical design, implementation, debugging, review, and delivery support. You can understand business requirements, ask the right questions, identify risks early, and translate technical direction into working production systems.

You care about good engineering principles, including SOLID, clean architecture, sensible abstractions, design patterns where appropriate, testability, separation of concerns, maintainability, and long-term supportability. You know when to keep things simple, when to introduce structure, and when a technical decision may create future complexity.

You are not just an implementer. You contribute to technical conversations, challenge ideas constructively, mentor other developers, and help raise the quality of the team around you.

You communicate clearly with developers, architects, QA, designers, product stakeholders, and client-facing teams. You are comfortable explaining technical decisions, trade-offs, risks, and delivery progress in a practical, professional way.

You use AI-assisted engineering tools in your day-to-day work as a serious productivity lever, not as “vibe coding”. You use these tools to accelerate delivery, improve feedback loops, explore options, and reduce repetitive work, while still applying strong judgement around design, correctness, readability, testing, maintainability, and security.

What you’ll do

• Design, build, and maintain production-grade APIs & Services using C# and .NET.
• Own backend features and technical workstreams from planning through to implementation, testing, release, and support.
• Design and implement service layers, business logic, integrations, data access layers, background services, and scheduled processing components.
• Work with SQL Server databases, including schema design, queries, indexes, stored procedures where appropriate, and performance considerations.
• Help shape technical approaches, system designs, implementation plans, and delivery trade-offs.
• Review architectural direction and contribute practical feedback before and during implementation.
• Break down complex technical work into clear, deliverable pieces for yourself and other developers.
• Write and maintain automated tests for core backend logic, integration points, and critical workflows.
• Debug, diagnose, and resolve issues across backend services, databases, APIs, integrations, infrastructure touchpoints, and client-facing flows.
• Collaborate with frontend, mobile, QA, design, product, architecture, and client-facing stakeholders to deliver complete working features.
• Participate in and lead code reviews, helping maintain strong engineering standards across the team.
• Mentor intermediate and junior developers through code reviews, pairing, technical discussions, and implementation guidance.
• Contribute to CI/CD pipelines, deployment processes, release quality, observability, logging, monitoring, and operational improvements where needed.
• Identify technical risks, security concerns, maintainability issues, and performance bottlenecks early.
• Use AI-assisted engineering tools responsibly to improve delivery speed, feedback loops, code quality, and technical decision-making.

Requirements

• Strong professional experience with C# and .NET / ASP.NET Core.
• Strong experience building, maintaining, and supporting REST APIs in production environments.
• Strong understanding of SQL Server, relational database design, query performance, indexing, and data modelling.
• Experience with data access patterns using tools such as Entity Framework Core, Dapper, or similar.
• Solid understanding of backend architecture, layering, separation of concerns, and maintainable service design.
• Ability to design and implement backend features with limited supervision.
• Ability to understand business and technical requirements, identify gaps, and ask the right questions before implementation.
• Comfortable making technical trade-offs and explaining the reasoning behind them.
• Strong understanding of authentication, authorisation, validation, error handling, logging, API security, and secure backend development practices.
• Strong engineering habits: clean code, good abstractions, pragmatic design, meaningful tests, and a quality-first mindset.
• Experience reviewing code and giving clear, constructive technical feedback.
• Ability to guide, mentor, and support less experienced developers.
• Ability to own features end-to-end, from design and implementation through to testing, release support, and production troubleshooting.
• Comfortable using Git and working in a collaborative development workflow.
• Comfortable participating in technical discussions with developers, architects, QA, product stakeholders, and client-facing teams.
• Cape Town based and available for regular office meetups in Claremont.
• Comfortable using AI-assisted engineering tools as a productivity lever, while still applying strong judgement around design, correctness, readability, testing, maintainability, and security.

Tech stack you should be comfortable with

We expect hands-on experience in several of the following:

Core requirements

• C#/.NET
• REST APIs
• SQL Server, Entity Framework Core and/or Dapper
• Git
• Backend architecture and design patterns
• Authentication and authorisation patterns
• Testing and debugging
• Technical ownership and communication

Expected senior-level experience / useful experience

• Azure & Azure DevOps
• Docker
• CI/CD
• Messaging or event-driven systems
• Background services / worker services
• API security
• Observability, logging, monitoring, and production diagnostics
• Performance tuning
• Integration-heavy systems
• Clean Architecture, modular architecture, or similar backend structuring approaches

You do not need to be an expert in everything listed, but you should have strong backend fundamentals, good technical judgement, and the ability to learn new tools and patterns quickly.

Nice-to-have (not required)

• Full-stack development experience with web technologies such as React, TypeScript, HTML, CSS, or similar.
• Experience with MVC, Razor Pages, Blazor, or other .NET-based web application patterns.
• Experience in a secondary backend language such as Node.js, Java, Python, or similar.
• Experience with messaging technologies such as RabbitMQ, LavinMQ, Kafka, Azure Service Bus, or similar.
• Experience with event-driven architecture, pub/sub patterns, fanout, retries, reconnect strategies, and topic design.
• Experience building secure portals, financial services systems, reporting systems, workflow systems, or integration-heavy platforms.
• Familiarity with cloud hosting, especially Azure.
• Experience with infrastructure, observability, logging, monitoring, or production support.
• Experience working in consulting, agency, or client-facing delivery environments.
• Experience helping shape technical decisions, not just implementing tickets.

Security mindset

You don’t need to be a security specialist, but you should have a strong baseline of secure engineering practices for web applications, mobile applications, and API integrations, and you should be comfortable discussing those practices during interviews. Security, quality, and maintainability are important parts of how we build software at Protium.

Compensation & benefits

Market related — we offer competitive salaries and meaningful employee benefits.

Final compensation will depend on experience, seniority, technical depth, and fit for the role. Benefits and employment structure will be discussed during the hiring process.

Hiring process (what to expect)

1. CV review + short Protium-specific motivation or cover letter
2. Get-to-know-you call/video
3. Technical interview
4. Optional: Short take-home assignment
   A focused backend/API task based on a small base project, targeted at approximately 2–4 hours
5. Optional: live extension or bug-fix session
   A short 30–45 minute session to see how you approach problems, reason through trade-offs, and use AI-assisted engineering tools while keeping quality high

We aim to keep the process pragmatic and respectful of your time. Depending on the role and your background, some stages may be shortened, combined, or skipped.

How to apply

Send us:

• Your CV
• A short Protium-specific motivation. 3–6 sentences is enough
• Links to GitHub, GitLab, shipped projects, APIs, technical writing, or other relevant work (optional, but recommended)