Synack’s Penetration Testing as a Service platform manages customers’ attack surfaces by discovering new assets, pentesting for critical vulnerabilities and gaining visibility into the root causes of security risks. We are committed to making the world more secure by harnessing a talented, vetted community of security researchers to deliver continuous penetration testing and vulnerability management, with actionable results. Synack's PTaaS platform has uncovered more than 71,000 exploitable vulnerabilities to date, protecting a growing list of Global 2000 customers and U.S. agencies in a FedRAMP Moderate Authorized environment. For more information, please visit www.synack.com.
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. Please view our candidate privacy policy.
This position has responsibility to ensure Synack’s security and privacy posture is maintained.
Salary is determined by a combination of factors including location, level, relevant experience, and skills. The compensation package for this position may also include equity, and benefits.
For more details about our benefits, please see our benefits overview. Then for the Employer code, enter: synack
Skills Required
- 7+ years of experience in distributed-systems and backend software engineering.
- Experience with AI technologies (LLMs, RAG, MCP, etc.).
- Excellent grasp of token usage optimization and LLM cost optimization techniques.
- Expert knowledge of golang (4+ years) and solid hands-on experience with Python.
- Strong experience and understanding of microservices, REST API design, gRPC, writing unit testing, BDD testing.
- Strong design skills required; UML is a bonus; exposure to Domain Driven Design desirable.
- Experience with asynchronous messaging technologies such as Google PubSub, Kafka.
- In depth knowledge of NoSQL and RDBMS technologies.
- Strong experience with Docker, Kubernetes, Cloud Environments (GCP preferred).
- Experience working on agile teams.
- Excellent communication and collaboration skills in all mediums.
- Experience working on and scaling a microservice-based application.
- A proven ability to thrive in a collaborative environment with different stakeholders and subject matter experts.
- Experience in a fast-paced startup environment.
- Experience in Cyber Security.
What We Do
Synack, the most trusted crowdsourced security testing platform, delivers smarter penetration testing for dynamic attack surfaces on a continuous cadence. The company’s hacker-powered, AI-enabled pen test provides access to the best worldwide talent, scalable and smart technology, and insights that secure our nation's critical infrastructure and leading brands and businesses.
