Software Engineer

Senior Software Engineer

Location: London, UK

Working arrangement: Hybrid, 3 days per week in the office

Employment type: Full-time, permanent

About the Company:

Our client is an early-stage technology company operating at the intersection of AI and cybersecurity. The company is building autonomous AI agents that help enterprises automate complex security testing and vulnerability assessment workflows. Its product is already being used by enterprise customers, and the team is focused on expanding its capabilities and evolving the underlying software.

The engineering team is small, hands-on and technically ambitious. Engineers have meaningful ownership of the software they build and work closely with the product to solve challenging problems, deliver new capabilities and maintain reliable production systems.

About the Role:

We are looking for a hands-on Senior Software Engineer with strong professional Python experience to help build and evolve the company's core product.

This is primarily a product software engineering role, with a strong backend focus. You will spend your time designing, implementing, testing, deploying and improving software used in real customer environments. You will take ownership of technical problems from the initial requirements through to production, making practical engineering decisions and understanding their impact on reliability, security and maintainability.

The role involves more than writing application code. You will work with APIs, databases, cloud services and distributed workflows, helping ensure that the product remains reliable as its capabilities and usage grow. You may also contribute to AI-driven functionality, including agent workflows and LLM integrations.

We are looking for an engineer who enjoys building software, can navigate complex technical problems independently and is comfortable working across different parts of the stack in a small team.

What You'll Do:

• Build and improve production software using Python, with a focus on backend services and core product functionality.
• Design, implement and maintain APIs, integrations and services that support customer-facing capabilities.
• Take ownership of features and technical problems from design through implementation, testing, deployment and ongoing production support.
• Work with SQL and relational databases to develop reliable data models and efficient queries.
• Build and maintain software that interacts with cloud services and production infrastructure.
• Contribute to distributed and asynchronous systems, including workflows involving long-running operations and background processing.
• Integrate AI-driven capabilities into the product, working with agents, LLMs and external tools where appropriate.
• Investigate production issues, diagnose failures and improve system reliability, performance and observability.
• Apply sound engineering practices around testing, code quality, maintainability and security.
• Collaborate closely with other engineers and product stakeholders, contributing ideas and taking responsibility for delivery.

What We're Looking For:

• Strong, hands-on professional experience with Python, demonstrated through building and maintaining real software rather than familiarity with the language alone.
• Solid software engineering fundamentals and experience developing backend applications, APIs or services.
• A track record of building, deploying and operating production software used by customers or internal users.
• Experience taking ownership of technical work, from implementation and testing through to deployment and production support.
• Good understanding of SQL, relational databases and data modelling.
• Experience with cloud-based applications and services, ideally AWS.
• Practical experience with containers, such as Docker, and an understanding of how applications are deployed and operated.
• Knowledge of software architecture, system reliability, performance and maintainability.
• Familiarity with distributed systems, asynchronous processing, concurrency or event-driven architectures.
• A pragmatic approach to problem-solving, with the ability to make sound technical decisions and work effectively in a small engineering team.
• A security-conscious approach to software development, including an awareness of how engineering decisions affect production systems.

Particularly Relevant Experience:

Experience in one or more of the following areas would be valuable:

• Building AI agents, LLM-powered applications or tool-integrated workflows.
• Developing software that uses AI to automate complex tasks or decision-making processes.
• Working with distributed systems, event-driven architectures, queues or long-running workflows.
• Using AWS, Docker, Kubernetes or Infrastructure as Code tools such as Terraform.
• Building reliable, observable and secure production services.
• Working on cybersecurity products, security automation, vulnerability assessment or offensive security tooling.
• Developing multi-tenant SaaS products or other systems used by enterprise customers.

You do not need to have experience in every area. We are particularly interested in engineers who combine strong Python development with solid software engineering fundamentals and a demonstrated ability to build and operate production systems. Experience with AI agents or cybersecurity is a valuable advantage, but depth of engineering experience and technical ownership are central to the role.

Why Join?

• Work on an AI-driven cybersecurity product already being used by enterprise customers.
• Take meaningful ownership of core product development in a small engineering team.
• Solve challenging problems involving backend engineering, AI, distributed systems and production reliability.
• Work closely with experienced technical leadership and contribute directly to the evolution of the product.
• Join at an early stage, with the opportunity to influence engineering decisions and how the platform develops.

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