Senior Backend Developer – C# .NET

Senior Backend Developer – C# .NET Aarhus, Denmark OR Arendal, Norway

Puzzel:
The Low-Down 🔍

Puzzel is a leading provider of cloud-based contact centre solutions, empowering businesses to deliver exceptional customer service. Our platform combines omnichannel contact centre, workforce management, and AI-driven analytics to optimize customer interactions and operational efficiency.

With 25 years’ experience since our foundation in Norway, we’re already #1 in the Nordics, growing rapidly in the UK and expanding into the Netherlands and Finland in 2024, but our ambition is to become the clear European market-leader in the coming years 🚀

• 2024 CX Awards Winner, ‘Best Mid-Market Contact Center Platform’
• Puzzel was recognised as the 'most innovative European-founded CCaaS provider' and top 3 globally by Frost & Sullivan in 2023
• Best Practices Company of the Year 2023
• Consistently high Glassdoor rating
• 2023 customer NPS score of 37
• Puzzel places high importance on work-life balance and flexible working hours - as recognised by Flexa, placing 16th overall for work:life balance in 2025!
• We are working with Mercer on salary benchmarking, to ensure pay equality and market competitiveness

• €57m revenue in FY 2024 (up from €50m in 2023)
• Currently ~300 employees
• Used by more than 1100 businesses across 40 countries
• Servicing ~60,000 customer service agents on a daily basis + 800 million customer interactions yearly

The Senior Backend Developer will be an integral part of our Core Platform team, who build and maintain the functionality of our core CX ecosystem: think /login, SMS Gateway, Voice Calls, Knowledgebase, Master Data – all of the core functionality that enables customers to get in touch with the customer service department and in turn, for the customer service agents to have access to information about the customer.

As part of the team, you’ll work on building and evolving these systems — ensuring that these critical systems are reliable, secure, and highly available – enabling seamless customer interactions and empowering agents with the real‑time information they need to deliver exceptional service.

It’s important to mention that this is an individual contributor role with no direct reports, so we're looking for hands on developers at a senior level.

• Design, build, and maintain scalable backend services powering our Core Platform Services.
• Write clean, maintainable, and well-documented code that supports high availability and rapid iteration.
• Collaborate closely with product, design
  , and other engineering teams to deliver performant and reliable features
• Design and maintain secure, well-documented APIs that enable seamless integration between core services and client applications across the CX ecosystem.
• Participate in system architecture discussions, contributing to design decisions and technical direction.
• Explore and apply new technologies to improve performance, scalability, and developer experience.
• Own the performance and optimization of critical services, identifying bottlenecks, reducing latency, and ensuring systems can scale to meet growing demand.
• Monitor system health and respond to incidents, implementing robust observability practices and participating in on‑call rotations to ensure platform reliability.

• 5 years of backend development experience working on a SaaS product, in a backend or fullstack capacity.
• Proven experience building and maintaining large‑scale
  distributed systems or high‑availability applications.
• Strong proficiency in C# (our primary language) or another modern backend language such as Java, or Go, with willingness to work primarily in C#.
• Solid understanding of system design, API development, and modern application architecture
  .
• Effective communication skills in English and a collaborative mindset.
• Strong focus on testing and quality
  , with experience writing unit, integration, and end‑to‑end tests to ensure system reliability.
• Understanding of security best practices
  , particularly around authentication, authorization, data protection, and secure API design.
• Experience working in agile environments with modern…