Solve hard problems where AI meets cybersecurity.
Open roles
Platform Engineer
Platform Engineer
The role
Own the core product platform from its external interfaces through the service and data layers. You will build the APIs and SDKs that connect Refractal to customer systems, along with the services, identity controls, and event contracts behind them.
Work directly with the founders and early customers to turn operational security needs into simple, reliable platform interfaces and operator tools.
What we offer
- Competitive salary, meaningful equity, and a performance-linked bonus.
- Direct influence over the product, architecture, engineering standards, and company direction.
- Real, high-consequence AI deployments rather than purely synthetic environments.
- London-based, in-person work, with UK Skilled Worker visa sponsorship and support for Global Talent applications.
What you'll work on
- Own stable, versioned platform APIs and SDKs, including client interfaces, compatibility rules, documentation, and examples.
- Build FastAPI services for enforcement decisions, evidence, policies, and red-team results.
- Design authentication, sessions, API keys, authorisation, and rigorous multi-tenant isolation.
- Build data and event interfaces, real-time streams, and a tamper-evident audit ledger.
- Create customer onboarding, policy integration, and operator dashboard workflows.
- Own testing and deployment across API compatibility, browser smoke tests, Cloud Run, and Cloud SQL.
What we're looking for
A product-minded platform engineer who makes complex systems clear and predictable and takes ownership from the data model to the customer integration.
- Strong backend experience with HTTP APIs; Python and FastAPI experience is preferred.
- Experience with observability, tracing, relational databases, and database migrations.
- Sound judgement around API design, versioning, SDKs, and compatibility.
- A strong understanding of authentication, authorisation, API keys, and multi-tenant access control.
- Good JavaScript and React skills for building operator-facing product surfaces.
- The ability to work independently and own technically uncertain customer problems.
How to apply
Apply on LinkedIn with your CV and tell us about the most interesting thing you have built and shipped, ideally something you owned end to end. Links to live products, open-source work, or technical write-ups are strongly encouraged.
Systems Engineer
Systems Engineer
The role
Own the services and infrastructure that keep Refractal secure and reliable in production. You will work across the enforcement runtime, data integrity, tenant isolation, agent tracing, model services, and cloud infrastructure.
Build systems that connect activity across agents, services, and tools, evaluate risk, apply decisions, and preserve the evidence behind them.
What we offer
- Competitive salary, meaningful equity, and a performance-linked bonus.
- Direct influence over the product, architecture, engineering standards, and company direction.
- The opportunity to establish Refractal's systems engineering function and grow into technical leadership.
- London-based, in-person work, with UK Skilled Worker visa sponsorship and support for Global Talent applications.
What you'll work on
- Build and operate a low-latency runtime enforcement pipeline with predictable failure behaviour.
- Own observability and tracing across agent actions, tool calls, model calls, and enforcement decisions.
- Build tamper-evident evidence storage and enforce multi-tenant isolation throughout every data path.
- Create reliable event and streaming services with safe handling for load, retries, backpressure, and disconnections.
- Build infrastructure for red-team jobs, evaluation workloads, and model-serving services.
- Own cloud infrastructure, continuous delivery, secrets, artefact verification, and production trust boundaries.
What we're looking for
A systems engineer who reasons carefully about latency, failure, isolation, integrity, and cost, and uses measurements rather than assumptions.
- Strong experience with backend, distributed, or infrastructure systems; Python experience is preferred.
- Production observability and distributed tracing experience, ideally with OpenTelemetry or similar tooling.
- Experience building responsive services under load with robust timeout, retry, and backpressure behaviour.
- Experience with Postgres, Row-Level Security, migrations, and multi-tenant access-control testing.
- Hands-on experience with containers, cloud infrastructure, continuous delivery, and operational security.
- The ability to work independently and own technically ambiguous production problems.
How to apply
Apply on LinkedIn with your CV and tell us about the most interesting system you have built, scaled, or secured. Links to open-source work, technical write-ups, or systems you have designed are strongly encouraged.
AI Research Engineer
AI Research Engineer
The role
Join as one of the first engineering hires after the technical co-founder. You will own core parts of the platform from day one: agent classification, runtime evidence pipelines, and policy enforcement across models and modalities.
This is a high-autonomy role with direct customer impact and a path towards leading the engineering organisation as we scale.
What we offer
- Competitive salary, meaningful equity, and a performance-linked bonus.
- Direct influence over the product, research agenda, and company direction.
- Real, high-consequence AI deployments rather than purely synthetic environments.
- London-based, in-person work, with UK Skilled Worker visa sponsorship and support for Global Talent applications.
What you'll work on
- Build the runtime classification stack that decides whether an agent's proposed action is authorised before it executes.
- Design action-boundary controls that allow, block, or redact sensitive data from flagged actions.
- Build evidence pipelines that record every AI action, verdict, and rationale.
- Compile natural-language company policies and regulation into executable runtime controls.
- Develop multimodal ingestion and detection across models, tools, and data types.
- Own systems end to end and ship them into real, high-consequence customer deployments.
What we're looking for
A technically exceptional builder who cares about getting AI safety and security right, and who grounds research in real-world impact.
- Typically 0-3 years of post-university experience building AI or machine learning systems.
- A strong foundation in computer science, machine learning, cybersecurity, or a related field.
- Evidence of exceptional building ability through production systems, research at a leading lab, startup work, or open source.
- A rigorous understanding of how AI systems fail and how adversaries can exploit them.
- The ability to move quickly, communicate clearly, and own complex technical problems independently.
How to apply
Complete the application form with your CV and a short note about the most interesting system you have broken, built, or studied. Links to research, write-ups, and open-source work are strongly encouraged. Our process is an intro call, a technical deep-dive, a short practical exercise, and an offer, typically within two weeks.
Security Researcher
Security Researcher
The role
Be Refractal's first dedicated AI security hire. Break agentic systems before adversaries do, then turn what you learn into repeatable evaluations, customer insights, and production security controls.
You will work across security research, offensive engineering, and product development, directly with the founders and our earliest customers.
What we offer
- Competitive salary, meaningful equity, and a performance-linked bonus.
- Direct influence over the product, research agenda, and company direction.
- The opportunity to establish Refractal's security research function and grow into technical leadership.
- London-based, in-person work, with UK Skilled Worker visa sponsorship and support for Global Talent applications.
What you'll work on
- Red-team production and pre-production agents across browser, code, enterprise, and multi-agent environments.
- Discover attacks involving prompt injection, goal manipulation, memory poisoning, tool abuse, identity, and data exfiltration.
- Develop realistic exploit chains across model, application, identity, tool, and infrastructure layers.
- Build automated attack agents, evaluation harnesses, and reusable security test suites.
- Turn research findings into detections, runtime evidence, policy controls, and product requirements.
- Assess customer deployments and communicate technically rigorous, actionable findings.
What we're looking for
An adversarial thinker with a builder's instinct who can move from an ambiguous attack hypothesis to a reproducible proof of concept.
- A strong foundation in security, computer science, machine learning, or a related field.
- Hands-on experience in offensive, application, cloud, product, or AI security.
- The ability to build security tooling and proof-of-concept exploits, ideally in Python and a systems language.
- Practical knowledge of modern agent architectures, including tool calling, retrieval, memory, orchestration, and permissions.
- Strong experimental discipline, clear communication, and ownership of technically ambiguous problems.
How to apply
Complete the application form with your CV and a short note about the most interesting system you have broken, built, or studied. Links to research, write-ups, open-source work, CTF profiles, or working exploits are strongly encouraged. Our process is an intro call, a technical deep-dive, a short practical exercise, and an offer, typically within two weeks.