Software Engineer, AI (Level determined by experience)

NetSPI+Synack is a leader in offensive security, combining elite human expertise with agentic AI to help organizations identify, validate, prioritize, and remediate exploitable risk across their entire attack surface. Its platform delivers expert-validated testing in depth, continuously, or on demand, from pre-production code to live production environments, so security teams can separate vulnerability noise from real risk, including the growing threat of AI-driven attacks. With global reach and more than 13 million hours of real-world offensive testing experience, NetSPI+Synack serves many of the world's largest enterprises and government organizations with one ambition: nothing left to exploit. We are looking for individuals with a collaborative, innovative, and customer-first mindset to join our team. Learn more about our award-winning workplace culture and get to know our A-Team at www.netspi.com/careers and www.synack.com/careers . We are looking for a Senior Software Engineer (AI), where you'll design and ship AI agents that plan, reason, drive security tooling and surface exploitable vulnerabilities, running autonomously inside sandboxed environments. It's a hands-on senior role spanning applied AI and cybersecurity. You'll own systems end to end and raise the technical bar for the team around you. Sounds interesting? Keep reading… Please note: This is a remote position based in the UK. We can only hire citizens of the United Kingdom for this role. Given the nature of the work, the role may be subject to nationality, residency and security-clearance checks. Here’s what you'll do • Build AI agents that automate penetration testing: planning, tool use, reasoning over findings, and acting safely within scope. • Stand up and run the sandboxed cyber-lab and range infrastructure, containerised on Kubernetes, where these agents execute offensive tooling. • Ship features from ideation through production, including evals, guardrails and monitoring. • Improve how our agents work: prompting, tool orchestration, evaluation, and cost. • Lead code reviews and design sessions, and help the engineers around you grow. • Work closely with our security researchers to translate how they hack into how our agents operate. Here’s what you’ll need • 4+ years of software engineering experience • Proven ability to build and scale production systems • Strong Python, polyglot codebase • Fluent or willing to learn Go • Hands-on experience building and operating production AI applications using LLMs and agentic frameworks (e.g., RAG, MCP, LangGraph or similar), including tool integration, prompt design, evaluation, guardrails, and token/cost optimization. • Demonstrate ability to create reliable agents (prompting, evaluation, guardrails, understanding of token and cost optimization • Capable leveraging Docker, Kubernetes, isolated sandbox, cloud experience GCP preferred • Brings a disciplined testing approach to microservices gPRC, API design, async messaging (Pub/Sub, Kafka) • Passionate desire to understand how systems get compromised • Clear communication • Collaborative ability to partner across teams Nice To Have • Offensive security experience: penetration testing, red teaming, CTF, or security tooling. • Experience driving security tools programmatically or automating an attack chain. • Startup experience, where scope is broad and priorities move fast. Ready to join us? Synack is committed to embracing diversity. Our people are our strength. Each addition to our team is an opportunity to grow and diversify our ideas, experiences, and viewpoints. We strive to be inclusive of Race, Ethnicity, Religion, Sex, LGBTQ+, Veterans, Disabilities, and Age. Synack welcomes you! As a candidate, Synack cares about your privacy. Pl