Senior Software Engineer

Menlo Security is the leader in Browser Security for human and agentic workforces. Our mission is to enable humans and agents to connect, communicate, and collaborate securely, without compromise. The Menlo Browser Security Platform protects organizations from cyberattacks by stopping threats across the web, documents, and email before they reach the user. With Menlo Agent Runtime Security (MARS), that protection now extends to the AI agents working alongside every employee. Menlo Security is trusted by major global businesses, including Fortune 500 companies and government agencies, to protect their most valuable asset, their data, and is backed by top-tier investors. Summary Menlo Security is hiring a Senior Software Engineer to join our Threat Protection and ShadowAI team in the UK. This team ensures that users can safely browse the web through Menlo's secure cloud — protecting them from malicious sites (including those built or operated with AI) and securing access to authorised web applications. The services this team builds are core to Menlo's secure enterprise browser for both humans and AI agents, which puts you at the centre of one of the most active problems in enterprise security right now: how organisations gain visibility into and control over unsanctioned AI usage without blocking it entirely. The team applies AI in how it builds as well — code assistants, AI-assisted test generation, and LLM-supported log and incident analysis — so you will be using these tools alongside defending against their misuse. Outcomes & KPIs Key Outcome(s) Owned: Reliable, performant delivery of Threat Protection and ShadowAI services that detect and control risky web and generative AI application usage for Menlo customers. End-to-end ownership of assigned features, from design through production operation and iteration. Success Metrics / KPIs: (drafted for hiring manager review and adjustment) Service availability and latency for owned components meet or exceed team SLOs. Features delivered on committed roadmap dates, with quality measured by post-release defect and rollback rates. Automated test coverage maintained or improved on owned code paths. Detection accuracy for AI application and malicious site coverage, measured by false positive and false negative rates. Mean time to detect and resolve production issues in owned services. What You'll Do Design, develop, and own new features and services in the Threat Protection and ShadowAI product area, contributing directly to Menlo's technical roadmap. Build highly available, scalable distributed systems and APIs, including multithreaded and asynchronous applications, with performance and security considered from the start. Build and refine the detection and policy capabilities that give customers visibility into generative AI and unsanctioned web application usage in their environments. Participate in building, deploying, and operating the Menlo Security platform in production, using dashboards, error reporting, metrics, and AI-assisted log and trace analysis to identify and resolve defects quickly. Use AI code assistants and AI-assisted test generation as part of your normal workflow to move faster, while applying your own judgement on correctness, security, and maintainability before anything ships. Partner with product, security, operations, and other cross-functional stakeholders to align on requirements, tradeoffs, and schedules. Write unit and automated tests, conduct code and design reviews for peers, and evaluate emerging technologies that could improve our products. Functional Competencies Required: 3-5 years of professional software development experience with one or more of NodeJS, Go, or Python. 3-5 years of hands-on experience with cloud services such as GCP and/or AWS. Working experience with Linux and standard development tooling such as git. Degree in Computer Science or a related field (BE, BTech, or Masters), or equivalent practical experience. Practical fluency with AI coding and debugging assistants, including sound judgement about when to rely on LLM output and when to verify it independently. Self-directed approach to problem solving, with the ability to pick up unfamiliar systems and technologies with limited guidance. Preferred / Nice to Have: Experience building large-scale web applications and REST APIs. Strong grounding in complex data structures and database technologies. Experience with containers, Docker, and Kubernetes. Experience with cloud infrastructure as code tooling such as Terraform. Familiarity with the Tornado web application framework and test automation. Track record of adapting and improving engineering practices such as test-driven development, continuous delivery, agile ceremonies, automation, and maintainable, testable code. Interest in or exposure to security, threat detection, or AI governance and safety. MSGL-I4 Follow us on LinkedIn! Why Menlo? At Menlo, we don't settle for the status quo — in our technology or our culture. How we think and act is just as important as what we build. Our culture is defined by five core mindsets: Proactive Leadership, Straight Talk, United Impact, Elevated Talent, and Customer-Compelled. We take ownership and drive outcomes without waiting to be told. We communicate directly and seek hard truths. We break down silos and win together. We hold a high bar for ourselves and the people around us. And we treat every customer interaction as mission-critical. If you're someone who sees it, owns it, solves it, and does it — you'll thrive here. All qualified applicants will receive consideration for employment without regard to race, sex, color, religion, sexual orientation, gender identity, national origin, protected veteran status, or on the basis of disability. TO ALL AGENCIES: Please, no phone calls or emails to any employee of Menlo Security outside of the Talent organization. Menlo Security’s policy is to only accept resumes from agencies via Ashby (ATS). Agencies must have a valid services agreement executed and must have been assigned by the Talent team to a specific requisition. Any resume submitted outside of this process will be deemed the sole property of Menlo Security. In the event a candidate submitted outside of this policy is hired, no fee or payment will be paid.