Senior Backend Engineer - Authorisation & User Management

Salary: £100,000
Location: London (Hybrid)

We're partnering with a fast-growing AI startup that's building cutting-edge technology to transform how enterprise organisations harness artificial intelligence. Working at the forefront of Generative AI, LLMs and agentic workflows, they're developing a secure platform capable of solving complex, real-world problems at scale.

They're now looking for an experienced Senior Backend Engineer to take ownership of the platform's identity, authorisation and user management capabilities, helping build secure, enterprise-grade systems that sit at the core of the product.

The Role

This is a unique opportunity to own one of the most critical areas of a modern AI platform. You'll design and build scalable backend services responsible for authentication, authorisation, permissions, user lifecycle management and enterprise identity integrations.

Working closely with Product, AI and Engineering teams, you'll shape the technical architecture behind secure access control while driving engineering best practices across a modern cloud-native platform.

Key Responsibilities

• Design, build and maintain secure backend services using TypeScript, Node.js and NestJS.

• Develop scalable authorisation, identity and user management systems for enterprise customers.

• Build secure APIs supporting authentication, permissions and user lifecycle management.

• Design resilient event-driven architectures and asynchronous backend workflows.

• Integrate enterprise identity solutions including SSO, SCIM and external identity providers.

• Ensure platform scalability, observability and production reliability.

• Collaborate closely with engineering teams on architecture, security and platform design.

• Mentor engineers through technical leadership, code reviews and best practice.

About You

You'll be a senior backend engineer who enjoys solving complex security and identity challenges within modern SaaS products.

You'll likely have:

• 5+ years' experience building production backend applications.

• Strong commercial experience with TypeScript, Node.js and NestJS.

• Experience designing scalable distributed systems and REST APIs.

• Strong experience building authentication, authorisation or identity management solutions.

• Experience with enterprise identity technologies such as SSO, SCIM, RBAC or identity providers.

• Strong knowledge of PostgreSQL, software architecture and cloud-native development.

• Excellent communication skills with the ability to mentor and collaborate across engineering teams.

Experience with Kubernetes, RabbitMQ, GraphQL, Prisma, multi-tenant SaaS platforms or AI technologies would be highly advantageous.

What's on Offer?

• £100,000 base salary.

• Hybrid working from the London office.

• The opportunity to work at the forefront of Generative AI and enterprise technology.

• High levels of ownership and technical autonomy.

• A collaborative engineering culture focused on innovation, learning and continuous improvement.

• The chance to build secure, enterprise-scale AI products used by leading organisations.

Sphere Digital Recruitment currently have a variety of job opportunities across digital so feel free to get in touch with us to find out how we can help you. Please take a look at our website.

Sphere is an equal opportunities employer. We encourage applications regardless of ethnic origin, race, religious beliefs, age, disability, gender or sexual orientation, and any other protected status as required by applicable law.

If you require any adjustments or additional support during the recruitment process for any reason whatsoever, please let us know.