Backend Software Engineer Developer C# .Net

Location: London City or Hybrid London with 3 days onsite depending on team.

Role overviewWe are hiring an experienced C# backend focused Software Engineer to join a financial services engineering team delivering business critical systems across Banking, Capital Markets, or Asset Management. This role is suited to someone who enjoys building resilient low latency services and APIs, working with complex data, and operating in environments where availability, auditability, and controls matter. You will contribute to greenfield builds and platform modernisation, and you will support key capabilities such as trade capture, post trade processing, risk and pricing services, market data distribution, client reporting, regulatory controls, and operational tooling.You will work closely with Quant, Trading, Risk, Product, and Operations stakeholders, translating requirements into robust engineering solutions. Depending on the team, you may be building real time services supporting trading and risk, or backend services powering digital channels and internal platforms within regulated financial environments.

What you will be doingYou will design, develop, and maintain backend applications using C# with .Net Core or .Net, typically building services and APIs that support high throughput, reliability, and secure data handling. You will create and enhance RESTful APIs and service integrations, applying strong object oriented design, SOLID principles, and appropriate design patterns. You will engineer for resilience and observability, building logging, metrics, tracing, and alerting into services so production behaviour is clear and supportable.You will work across the full software development lifecycle from discovery and design through build, automated testing, deployment, and production support. You will write and optimise SQL for large datasets, most commonly SQL Server and sometimes Oracle, ensuring performance, consistency, and appropriate indexing strategies. You will integrate with upstream and downstream systems such as market data feeds, order and execution management systems, risk engines, reference data platforms, and messaging layers. Many teams rely on event driven patterns, so experience with queues and streaming technologies is valuable.

Within financial services you will also operate within strong governance. You will contribute to secure coding practices, peer review standards, and change controls. You will support non functional requirements such as latency, throughput, fault tolerance, disaster recovery, and data retention. You will collaborate in agile delivery, contribute to estimation and planning, and maintain high standards of documentation, especially where audit or regulatory evidence is required.

Technology and toolsCore stack includes C#, .Net Core or .Net, ASP.Net, REST APIs, OOP, design patterns, and SQL Server. Financial services environments commonly use messaging and integration tooling such as Kafka, RabbitMQ, MQ, or service buses, plus API standards such as OpenAPI Swagger. Many teams use cloud platforms such as Azure or AWS, containerisation with Docker and Kubernetes, and CI CD with Git based pipelines. Typical delivery tools include Jira and Confluence. Testing approaches may include unit testing, integration testing, TDD, and BDD.Additional tooling may include TeamCity, Octopus, Jenkins, Azure DevOps, GitHub Actions, SonarQube, Splunk, ELK, Grafana, Prometheus, and automated test tooling. Some roles include limited front end work using JavaScript and React. Legacy platform exposure can include WinForms or WPF, particularly within older trading or risk applications.

Financial services domain exposure that can helpExperience in any of the following will help you ramp up quicklyTrade lifecycle from order and execution through confirmation, settlement, and reconciliationMarket data concepts including pricing, curves, reference data, and symbologyRisk domains such as market risk, credit risk, counterparty exposure, and PnL explainControls and governance, including audit trails, approvals, segregation of duties, and operational resilienceRegulatory or reporting familiarity such as transaction reporting, best execution, data lineage, and retention obligations

What we are looking forYou have strong backend engineering experience with C# and .Net, including building production grade services and APIs. You are confident working with relational databases and writing efficient SQL, and you understand performance considerations at scale. You have solid software engineering fundamentals, including clean code, data structures, algorithms, and design principles. You communicate clearly, collaborate well with technical and non technical stakeholders, and take ownership of delivery in a fast paced environment where priorities can change quickly. Financial services experience is strongly preferred, but strong engineers from other high availability domains will be considered.

Nice to haveExperience with event driven architectures and messaging, cloud exposure in Azure or AWS, containerisation, DevOps and CI CD maturity, automated testing, observability tooling, and experience working in regulated environments such as banking, asset management, insurance, or capital markets. Exposure to low latency or high throughput systems is a plus.