Principal Software Engineer - XTM One

The Company

Founded in 2022, Filigran is a global cybersecurity company on a mission to empower defense teams to be proactive through open-source solutions that uncover threats and drive action.

Filigran stands out in the cybersecurity ecosystem through its open-source, AI-powered and threat-informed approach to Continuous Threat Exposure Management (CTEM). Our eXtended Threat Management (XTM) platform brings together threat intelligence, exposure validation and cyber risk reduction, enabling organizations to better understand their threat landscape and take action.

At the heart of Filigran is our open-source approach. Our vision is to unite defenders into a global community to make security more open, resilient and collaborative.

As Filigran continues to scale globally, we are building the organization, infrastructure and capabilities needed for our next stage of growth. How we scale matters just as much as how fast we scale: our CORE values: Cohesion, Openness, Responsibility and Equity shape how we work together, make decisions and build for the future.

The Role

We're looking for a Principal Software Engineer to define and drive the technical direction of XTM One , Filigran's AI platform for threat informed defense and the agentic core of the XTM Suite.

XTM One creates and runs cybersecurity expert AI agents and dispatches their intelligence across OpenCTI, OpenAEV and OpenGRC. It also hosts the suite's shared commons (unified authentication, consolidated datasets, configuration) and ships both as SaaS and on premises. Every XTM product connects to it, which makes its architecture one of the most structuring technical decisions at Filigran.

This is not a management role: no headcount, no sprints. You own the technical craft, standards and vision of XTM One, and you carry them into the XTM Foundation, where the engineering principles shared by all products are set for the 60+ engineers at Filigran.

Your Responsibilities

Vision & architecture

• Define and carry the technical vision of XTM One over the long term, with technical and product leadership.
• Own the platform architecture : agent runtime and orchestration, tool and MCP integrations, data and context layers, APIs, permission model, shared commons.
• Design for SaaS and on premises from day one: multitenancy, isolation, upgrade paths, configuration, operability in customer environments.
• Arbitrate key decisions on scalability, resilience, security, maintainability and cost, including LLM latency and inference cost.

Standards & quality

• Define the team's technical principles (architecture patterns, code quality, tooling, CI/CD, testing, development with AI assistants) and get them applied through docs, reviews, pairing and example.
• Set the bar for observability and reliability of nondeterministic AI workloads: metrics, logs, traces, evaluations, and guardrails that make agent behavior measurable and debuggable in production.
• Keep the right balance between features, technical debt and innovation.

Integration across products & XTM Foundation

• Define how OpenCTI, OpenAEV, OpenGRC and future products integrate with XTM One : contracts, authentication, data exchange, versioning.
• Be a full member of the XTM Foundation : bring the XTM One perspective in, carry its decisions back, and keep coherence with the other Principal and Staff Engineers.

In the code

• Write production code, prototype new approaches before the team adopts them, review critical PRs so that feedback teaches, and unblock engineers.

Who You'll Work With

• Reports to: VP of Technology
• Key collaborators: XTM One engineering team and its verticals; XTM Foundation (Principal and Staff Engineers across OpenCTI, OpenAEV, OpenGRC); Product leadership; open source contributors.
• Working model: embedded in the XTM One team, with regular XTM Foundation work.

Profile We're Looking For

• 10+ years in software engineering, with technical leadership on complex production platforms.
• Strong fullstack background, with a backend and architecture focus. You master TypeScript and Python , the core languages of XTM One, and you can take a feature from the data model all the way to the UI.
• Strong system design : distributed systems, scalability, performance, security, observability.
• A 360° view of software engineering : product need, design, code and tests, CI/CD, packaging and release, infrastructure and deployment, production operations, monitoring, incident response. A container image or an upgrade path is as familiar to you as an API contract.
• Built and operated platforms delivered both as SaaS and on premises , including multitenancy and enterprise constraints.
• Strong AI affinity. You've been building with LLMs by choice for a year or two, with LLM systems in production : agent frameworks, tool calling, MCP, RAG and vector search, evaluation, and the discipline to make them reliable.
• Technical watch is part of …