Experienced .NET / C# Engineer

Insightful Technology; Greater London; On-site; GBP 70,000 - 110,000; Full time

Job summary

Insightful Technology is seeking a seasoned .NET / C# engineer to join our core platform team. You will own and optimize high-throughput distributed systems running in our on-prem datacentres, focusing on performance, security and data models, with engagement from product and operations colleagues.

Ideal candidates have deep experience with .NET Framework and the latest .NET / C# iterations, strong relational database skills (MS SQL Server), and a pragmatic, quality-driven approach to software

Qualifications

• Experience building and maintaining high-throughput distributed systems.
• Strong understanding of C#/.NET across versions and architectures.
• Proven ability to work with large relational databases and data models.

Responsibilities

• Develop, enhance, test and support .NET distributed systems.
• Modernize legacy .NET Framework code and migrate to .NET.
• Collaborate with DBA and operations teams to maintain data estates and performance.
• Improve reliability, resilience, and business value of core systems.
• Participate in design decisions and code reviews; ensure remaining aligned with industry standards.

Skills

C# programming

ASP.NET

MS SQL Server

APIs & integration

Distributed systems

Performance & scalability

Entity Framework Core

LINQ

Asynchronous programming

OOP fundamentals

Tools

Git

CI/CD tooling

Job description

We are looking for a seasoned and highly skilled .NET / C# engineer who has experience across .NET Framework, relational databases, and the latest iterations of .NET and C#. The role is suited for someone with a deep understanding of distributed, high throughput systems handling very large data volumes where performance and efficiency are key, as well as complex relational databases. You will be working closely with fellow developers, product colleagues and other stakeholders.

The engineer will work alongside our main engineering team to build, run, maintain, optimise, and support the company’s core platform deployed on servers physically located within our own datacentres. They will take ownership of the performance, security, and evolution of the core technical functionality as well as the underlying data models. High performance, stability, and resilience play a key role. The team’s success will be defined by a stable and resilient system, minimal downtime, fast recovery, high performance, high stakeholder confidence, and the ability to adapt to incoming product and business requirements in a fast-paced environment.

This role would suit a driven problem-solver who combines strong technical judgement with curiosity, pragmatism and a genuine commitment to technical excellence.

Key Responsibilities

Role Description

We are looking for a seasoned and highly skilled .NET / C# engineer who has experience across .NET Framework, relational databases, and the latest iterations of .NET and C#. The role is suited for someone with a deep understanding of distributed, high throughput systems handling very large data volumes where performance and efficiency are key, as well as complex relational databases. You will be working closely with fellow developers, product colleagues and other stakeholders.

The engineer will work alongside our main engineering team to build, run, maintain, optimise, and support the company’s core platform deployed on servers physically located within our own datacentres. They will take ownership of the performance, security, and evolution of the core technical functionality as well as the underlying data models. High performance, stability, and resilience play a key role. The team’s success will be defined by a stable and resilient system, minimal downtime, fast recovery, high performance, high stakeholder confidence, and the ability to adapt to incoming product and business requirements in a fast-paced environment.

This role would suit a driven problem-solver who combines strong technical judgement with curiosity, pragmatism and a genuine commitment to technical excellence.

Key Responsibilities

• Develop, enhance, test and support .NET and .NET Framework distributed systems.
• Modernize legacy .NET Framework code and migrate it to .NET.
• Work alongside the DBA and the operations team to help keep the highly complex relational databases estate performing within expectations.
• Work on the company’s core systems, helping to improve reliability, resilience, usability and business value.
• Collaborate with product, engineering and other teams within the business to understand requirements and translate them into workable technical solutions.
• Build and maintain system integrations with internal systems as well as external platforms and services.
• Support the ongoing improvement and maintenance of existing applications, including troubleshooting defects, performance issues and production incidents.
• Contribute to technical design decisions, ensuring solutions are resilient, performant, supportable and aligned to industry standards and practices.
• Write clean, maintainable code and follow agreed standards for version control, testing, deployment and documentation.
• Participate in code reviews, peer support and knowledge sharing within the team.
• Assist with release activity, deployment processes and post-release support where required.
• Work with Git and CI/CD tooling to support structured software delivery.
• Contribute to a collaborative, delivery-focused team culture and support continuous improvement in the way they develop and support software.
• In addition to the duties listed above, the jobholder is expected to perform other ad-hoc duties assigned by the Head of Engineering and / or the Lead Engineer from time to time.
• All colleagues are encouraged to take responsibility for personal development initiatives within the scope of their role, and to encourage the development of others.

Required experience and skillsMandatory

• Experience engineering software using C#, .NET, Asp.NET, .NET Framework, MS SQL Server.
• Experience building APIs, web services, system integrations.
• Experience building and supporting high throughput distributed systems.
• Experience with relational DBs and large data volumes in high throughput distributed systems.
• Experience engineering software systems from a performance, scalability, resilience, high availability, and high throughput perspective.
• Experience working with on premises systems and .NET legacy code.
• Excellent understanding of C# version 12, .NET version 8, preferably their more recent versions, as well as .NET Framework 2.0 and above.
• Excellent understanding of, Entity Framework Core, LINQ, and collections.
• Excellent understanding of Asp.NET, associated concepts, error handling, and request lifecycle.
• Excellent understanding of asynchronous programming, generics, data types, and memory management in C#.
• Excellent understanding of object-oriented programming and software engineering fundamentals.
• Excellent understanding around complexity, performance, and scalability of software systems.
• Excellent understanding of enterprise design patterns and modern enterprise architecture.
• Excellent understanding of process related concepts such as tasks, threads, processes, concurrency.
• Very good understanding of relational database, database fundamentals, performance aspects, and indexes on Microsoft SQL Server.
• Good understanding of ADO.NET and early .NET Framework data access technologies.
• Good understanding of unit testing and associated technologies.

Desirable

• Experience leveraging AI as a coding tool and AI agents to accelerate the software engineering process.
• Experience working in a fast paced, continuously evolving, and challenging environment.
• Understanding of software testing, particularly test automation and relevant technologies.
• Understanding of CI / CD concepts, pipelines, relevant systems and technologies.