Senior Software Engineer, Platform Engineering - Identity - Selby Jennings

Senior Software Engineer, Identity & Authentication Platform Engineering

Our client is an exceptional global investment firm renowned for building world-class technology that sits at the heart of its research and trading operations. With a reputation for engineering excellence, cutting-edge infrastructure, and a highly collaborative culture, they are continuing to invest heavily in their Platform Engineering function. They are now seeking a Senior Software Engineer to help shape the firm's next-generation identity, authentication, and authorization platforms, which underpin every engineer, application, service, and trading workflow across the organisation.

This is a highly strategic engineering role focused on building the authentication and identity infrastructure that secures and enables the firm's entire technology estate. They are looking for an engineer who is passionate about modern identity systems, authentication architecture, and large-scale distributed platforms. The ideal candidate will combine deep software engineering expertise with a strong ownership mentality, taking responsibility for designing and building resilient authentication, authorization, and access-control solutions that operate at massive scale while enabling developers to move faster and more securely.

Key Responsibilities

• Architect, build, and enhance mission-critical authentication and authorization platforms supporting research, engineering, and live trading environments.
• Design highly scalable identity and access management solutions capable of handling tens of millions of requests per day.
• Develop systems supporting human, non-human, workload, and AI-driven identities across the firm's technology ecosystem.
• Build low-latency, highly available authentication services with a focus on security, performance, and reliability.
• Partner closely with Information Security, Infrastructure, and AI Engineering teams to define and implement identity strategy and access-control frameworks.
• Develop developer platforms, SDKs, APIs, and self-service tools that simplify authentication and authorization adoption across engineering teams.
• Build developer acceleration tooling leveraging LLMs, intelligent agents, and AI-assisted engineering workflows.
• Contribute to firmwide engineering standards, architectures, and frameworks that improve consistency, security, and operational efficiency.
• Champion DevOps and SRE best practices, including observability, automation, CI/CD, and infrastructure as code.
• Participate in production support, incident management, and on-call responsibilities for critical platform services.

Key Skills & Experience

• 10+ years of software engineering experience building and operating large-scale production systems.
• Strong commercial development experience with Go and Python.
• Deep expertise in authentication, authorization, identity management, and access-control systems.
• Strong understanding of OAuth 2.0, JWT, SpiceDB, OpenFGA, or similar authentication and authorization technologies.
• Experience designing and building modern identity platforms supporting human, workload, machine, and service identities.
• Proven experience operating high-throughput, distributed systems with demanding performance and availability requirements.
• Strong experience with Kubernetes, containerisation, and cloud-native architectures.
• Ability to design scalable platform architectures and drive complex engineering initiatives from concept to production.
• Exposure to agentic AI frameworks, LLM tooling, or AI-powered developer productivity platforms.
• Strong understanding of DevOps, SRE, automation, and infrastructure engineering principles.
• Excellent communication skills with the ability to produce high-quality technical documentation, architecture proposals, and engineering standards.
• A highly collaborative, proactive engineer who thrives in fast-paced environments and enjoys solving complex platform and identity challenges.