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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Principal Software Engineer - **Company:** Filigran - **Location:** France (Remote available) - **Experience:** Expert - **Contract:** Permanent contract - **Skills:** Application Programming Interfaces (APIs), Artificial Intelligence, Architectural Patterns, User Authentication, Software as a Service, Software Quality, Computer Telephony Integration, Continuous Integration, Distributed Systems, Electronic Data Interchange (EDI), Python (Programming Language), Open Source Technology, Search Technologies, Software Engineering, TypeScript, Management of Software Versions, Working Model 2D, Retrieval-Augmented Generation, Large Language Models, Mitre Att&ck, Technical Debt, Backend, Agentic-AI, AI Platforms, Production Code - **Published:** November 13, 2026 - **Apply:** https://startup.jobs/principal-software-engineer-xtm-one-filigran-10757368 ## About the Role * 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 the job. You keep up with your craft deliberately (reading, experimenting, prototyping) and turn what you learn into concrete proposals. * You define and carry technical standards: you raise the bar on a team, you don't just follow it. * Excellent written communication in English: design docs, ADRs and review comments that others learn from. * Autonomous and at ease in a remote, asynchronous culture; you drive problems to resolution and enable others instead of becoming a bottleneck. * Bonus: cybersecurity domain knowledge (CTI, CTEM, MITRE ATT&CK, STIX/TAXII); extensible plugin or tool ecosystems; open source contributions or maintainership. ## Description 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., 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.