Senior C# Backend Engineer for Identity & Authorization

Harnham - Data & Analytics Recruitment; City Of London; On-site; GBP 101,000 - 120,000; Full time

Job summary

Harnham - Data & Analytics Recruitment is seeking a Senior C# Backend Engineer for a London-based, greenfield platform programme. You will build core identity and authorisation services consumed by AI-native apps and microservices, shaping architecture and standards.

The role focuses on secure IAM, policy evaluation, and scalable platform services, with opportunities to influence across the tech stack including API Gateways and Kubernetes integrations.

Qualifications

• Strong backend development in C#/.NET; Java considered.
• Experience building REST APIs in microservices.

Responsibilities

• Develop and maintain authorisation SDKs, APIs and identity services.
• Design secure IAM capabilities using OAuth2, JWT, and OIDC.

Skills

C#/.NET

Java (considered)

REST APIs

OAuth2 / JWT / OIDC

Identity & access management

RBAC / ReBAC / ACL

Policy-as-code

System architecture / distributed

SDK design

OpenID Connect

Tools

Kubernetes

API Gateway

Service Mesh

Neo4j

OpenFGA / SpiceDB / OPA

Redis

Kafka

Job description

Harnham - Data & Analytics Recruitment is seeking a Senior C# Backend Engineer for a London-based, greenfield platform programme. You will build core identity and authorisation services consumed by AI-native apps and microservices, shaping architecture and standards.

The role focuses on secure IAM, policy evaluation, and scalable platform services, with opportunities to influence across the tech stack including API Gateways and Kubernetes integrations.