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# Senior C# Backend Engineer

- **Company:** Harnham
- **Location:** London, UK
- **Experience:** Expert
- **Salary:** £143,000.0 - £169,000.0
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), .NET Framework, Application Programming Interfaces (APIs), Artificial Intelligence, User Authentication, Automation of Tests, C Sharp (Programming Language), Cloud Engineering, Distributed Systems, Identity and Access Management, Neo4j, OAuth, OpenID, Role-Based Access Control, Redis, Openid Connect, JSON Web Token, Systems Integration, Policy as Code, Performance Testing, Istio, System Availability, Backend, Kubernetes, Apache Kafka, Api Gateway, Restful APIs, Microservices
- **Published:** September 26, 2026
- **Apply:** https://www.reed.co.uk/jobs/senior-c-backend-engineer/57394157

## About the Role

* Strong experience developing backend applications using C#/.NET, with Java also considered.
 * Expertise building and supporting REST APIs within microservices-based environments.
 * Strong understanding of identity, authentication, and authorisation concepts.
 * Experience working with OAuth2, JWT, and OpenID Connect.
 * Knowledge of distributed systems and graph modelling principles.
 * Ability to design and develop scalable platform services and developer-facing SDKs.
 * Experience integrating systems with Kubernetes, API Gateway technologies, or Service Mesh environments.
 * Understanding of policy-based access control, RBAC, ReBAC, ACL, or policy-as-code frameworks.
 * Exposure to technologies such as Neo4j, OpenFGA, SpiceDB, OPA, Redis, or Kafka would be beneficial., If you are a Senior C# Backend Engineer with experience in identity, authorisation, distributed systems, and cloud-native architectures, apply today to learn more about this exciting contract opportunity., * c#
 * java
 * .net
 * software
 * engineer
 * rbac
 * kubernetes neo4j

## Description

* Develop and maintain authorisation SDKs, Policy APIs, identity services, and authorisation microservices.
 * Design and implement secure identity and access management capabilities using OAuth2, JWT, and OIDC standards.
 * Build authorisation models including RBAC, ReBAC, ACL, policy evaluation, delegated administration, and permission inheritance.
 * Develop integrations with API Gateway, AI Gateway, Kubernetes, and Service Mesh technologies.
 * Contribute to distributed systems design, graph-based relationship modelling, and scalable microservices architecture.
 * Create automated tests, authorisation regression suites, and performance testing frameworks to ensure platform reliability.