Senior Software Engineer

About the Client: Our client is an early-stage technology company operating at the intersection of AI and cybersecurity. The company is building AI agents that automate complex security testing and assessment workflows, with the product already being used by enterprise customers. The engineering team is small and works across product engineering, backend systems, cloud infrastructure and AI-driven software. Engineers have significant ownership over the systems they build and are expected to work closely with the product as the platform evolves. About the Role: The company is looking for a hands-on Senior Software Engineer to help build and evolve production software used by real customers.This is primarily a Product Software Engineering role. You will be expected to build software rather than work mainly on infrastructure, architecture or technical strategy. The role involves taking ownership of features and technical problems from design and implementation through deployment, production operation and ongoing improvement.Python is the primary engineering language, with strong experience in backend development expected. You will also work with SQL, AWS, cloud infrastructure, containers and Infrastructure as Code, alongside distributed systems and AI-driven software.The role is suited to an engineer who is comfortable working across the stack when needed, can make pragmatic technical decisions and enjoys solving complex problems in a small, technically ambitious environment. What You’ll Be Doing: Building and evolving production backend and product functionality using PythonDesigning and developing APIs and services used by customersTaking features from an initial problem or requirement through implementation, deployment and productionWorking with AWS and cloud infrastructure alongside application codeBuilding and operating containerised services and deployment infrastructureWorking with SQL and relational databasesDesigning systems that are reliable, scalable and maintainableWorking with distributed, asynchronous or long-running workflows where relevantContributing to AI-driven features, including AI agents and LLM-based functionalityInvestigating production issues and improving reliability, performance and observabilityMaking practical engineering decisions with a strong awareness of security and operational impact What We’re Looking For: Strong professional, hands-on Python experienceProven experience building and operating production softwareStrong backend and API development experienceExperience building software used by real customers or usersExperience with AWS or another major cloud platformGood SQL and relational database experienceExperience with Docker or other container technologiesExperience with Infrastructure as Code, ideally TerraformUnderstanding of scalability, reliability, concurrency or distributed systemsAbility to take ownership of technical problems and work independentlyA strong security mindset and awareness of how software decisions affect production systems Particularly Relevant Experience: Experience with AI agents, LLM applications, RAG, Kubernetes, Terraform, observability, distributed workflow systems, security engineering, offensive security or multi-tenant SaaS platforms would be particularly relevant. You do not need experience across every area. The most important factors are strong software engineering fundamentals, substantial hands-on Python development and a track record of building and operating real production software. Location: London, with 3 days per week in the office. By submitting your application, you agree to the processing of your personal data in accordance with our Privacy Policy.