Backend Engineer

About the role

We are looking for a Backend Engineer to help design and build core platform capabilities that underpin real-time control, security, and observability for agentic systems.

This is not a narrowly scoped feature role.

This is for someone who can:
• Build and maintain high-performance backend services that sit in critical execution paths
• Build systems that handle request/response flows, enforcement logic, and real-time decisioning
• Work with authentication and authorisation protocols (e.g. OAuth) to securely manage identity and access
• Develop integrations with external systems, including identity providers and third-party platforms
• Write efficient, reliable code that performs under load and supports low-latency requirements
• Contribute to system design across multiple parts of the platform as the product evolves
• Help ensure security, correctness, and observability are built into all layers of the system

This role is built for a junior to mid-level engineer who wants to grow quickly. You will contribute directly to core product capabilities, work alongside senior engineers on system design, and be supported to take on increasing ownership as you develop. Working as part of a high-calibre engineering team, you will thrive in a fast-paced environment where performance, reliability, and clean design are critical.

What you’ll bring

Experience
• 3–5 years’ professional software engineering experience, including building or maintaining production backend systems
• Some exposure to systems in the request path (e.g. APIs, gateways, middleware, or similar)
• Ownership mentality and comfort working with incomplete requirements, asking the right questions to fill the gaps
• Pragmatic approach that balances speed with long-term maintainability
• Eagerness to learn from senior engineers and take on increasing responsibility
• A degree in Computer Science or a related STEM subject is a nice to have, but equivalent practical experience is just as valued

Backend Systems & Architecture
• Experience building backend services, with an interest in designing for scale
• Working understanding of distributed systems concepts such as latency, throughput, and fault tolerance
• Familiarity with handling high-throughput or low-latency systems
• Appreciation for building systems that are observable, reliable, and secure

Authentication & Integrations
• Understanding of authentication and authorisation protocols (OAuth, OIDC, etc.)
• Exposure to integrating with identity providers (e.g. Okta, Azure AD, Auth0) or similar external systems
• Familiarity with secure session handling, token validation, and access control

Programming
• Commercial experience with .NET (C#) and SQL, using modern engineering practices
• Exposure to building or running services on Azure or AWS
• Experience writing performant, production-quality code
• Understanding of testing, CI/CD, and software engineering best practices

Reliability & Security
• Interest in building systems that operate reliably under load
• Understanding of secure coding practices and backend security principles
• Awareness of common vulnerabilities in authentication flows and API systems

Nice to have

AI tools

• Experience with Copilot, Cursor, Claude, or similar AI-assisted development tools

AI systems

• Exposure to LLM-powered systems, agent frameworks, or tool orchestration patterns
• Interest in how agent actions and execution context can be structured for analysis

How we work

• Small, dynamic, high-calibre team
• Incomplete requirements are normal; shaping solutions is part of the job
• Code quality, consistency, and architecture are considered at the earliest phase of design to avoid accumulation of technical debt
• Close collaboration between frontend, backend, ML, DevOps and platform engineers

This is a role for someone who wants impact, ownership and intellectual challenge.

About us

Every generational shift in computing requires a new layer of security infrastructure. In today's agentic era, Outerlimit provides the world's first decentralised security and authorisation layer designed specifically for securing Agentic AI.

We are backed by Evolution Equity Partners, AlbionVC and Crane Venture Partners, and our founding team has a proven track record of defining AI security landscapes, building market-leading security products and scaling businesses from startup to scale-up to exit.

Our values

Seek the truth: We're deeply curious, and we don't settle for the easy answer. Clarity beats comfort.

We own it: No job too small, no job too big. If it needs doing, we don't wait to be asked.

Never complacent: Good enough today isn't good enough tomorrow. We aspire to relentless improvement.

Do the right thing: Especially when it's hard, when no one's watching, and under pressure.

Why join Outerlimit

Real ownership: meaningful equity for everyone. When Outerlimit wins, you win.

Top-of-market pay, matched by benefits built to attract the best.

Flagship offices in London King's Cross and New York City, with flexibility in how you work.

The whole team together in one room at least quarterly.

A real budget for conferences, courses, books and gear.