Software Engineer (Internal Tools and Services)

Refractal is an AI security company building the infrastructure organisations need to defend against autonomous AI threats. 2026 has shown that generally capable intelligence is here. The challenge now is modernising security to stop AI-enabled threats, whether they come from internal agents going rogue or from attackers using AI to become more dangerous.

Refractal was founded on cybersecurity and AI expertise from MIT, Microsoft, NASA and the U.S. Navy. Our product lets organisations detect AI-enabled threats at low cost without sacrificing detection quality. We take a practical approach to AI risk, combining proven cybersecurity methods with frontier AI security research.

Today, we work with governments and organisations that can't afford to get security wrong. We're backed by leading deep-tech and cybersecurity investors and are growing the team to deliver on this mission.

You'll build the internal tools and services that keep Refractal running, from the systems our engineering, research and customer teams use every day to the backend services behind the product. The role suits someone who likes ownership, makes practical engineering decisions and wants to improve how a small team works.

• Build internal tools for our engineering, research and customer-facing teams, such as admin consoles, deployment and support tooling, and data utilities.
• Develop and maintain backend services and APIs behind the product, with clear interfaces and documentation.
• Automate repetitive work across engineering and operations, from testing and release checks to customer onboarding.
• Strengthen reliability and security through testing, code review, monitoring and investigation of production issues.
• Use modern AI software engineering tools thoughtfully, taking responsibility for understanding, reviewing and testing every change you ship.

Success in your first six months

• Internal tools you built are in daily use and save the team measurable time.
• The services you own have useful tests, clear documentation and enough visibility to diagnose problems.
• You've helped the team use AI tools more effectively while keeping code quality high.

• Experience building internal platforms, developer tooling or workflow automation.
• Familiarity with security-sensitive systems, access controls or auditability.
• Montenegrin, Serbian, Bosnian or Croatian.

Our values

Radical transparency. We believe the best work happens when everyone feels able to give and receive honest, constructive feedback.

Public service. We see AI security as a form of public service. Getting the AI transition right means putting the right infrastructure in place to manage the threats that come with it, and our work helps protect the institutions and services society depends on.

Fail fast. We test ideas early, seek feedback and learn quickly. We experiment rapidly and change course when something isn't working, without compromising on security.

Pragmatism, not dogmatism. We choose approaches based on how well they solve the problem. That means combining established cybersecurity methods with frontier AI research, questioning our assumptions, and changing our minds when the evidence changes.

• Experience building and maintaining software, with strong fundamentals in system design, debugging and testing.
• Ability to build clear APIs and work confidently with databases and backend services.
• Familiarity with current AI coding assistants or agents, and judgement about where they help and where their output needs scrutiny.
• A habit of understanding the code you ship, checking assumptions and validating behaviour beyond whether it appears to work.
• Ability to break down ambiguous problems, communicate trade-offs and own the quality of your work.
• Salary: €25,000–€70,000 gross per year
• Competitive equity to share in Refractal's growth
• Pension contribution
• Private medical and dental cover
• Visa and relocation support