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Principal Software Engineer

Microsoft Corporation

Geneva, Switzerland, Switzerland Full-time February 26, 2026

Found Description

**Overview**



Microsoft 365 Copilot is transforming productivity by integrating large language models with user data, Microsoft Graph, and the web. At the core of this innovation is the **Substrate Intelligence Platform (DSX)** team, which powers **personalized, secure, and scalable Copilot experiences** across Microsoft 365—Teams, Word, Excel, PowerPoint, OneNote, and beyond.



Our team is pioneering the **infrastructure for tenant‑isolated fine‑tuning** , a foundational platform capability that enables customers to safely personalize Copilot agents using their own data. This includes support for leading OpenAI models (e.g., GPT‑5, O4 Mini) and open‑source models such as Qwen, Mistral, and GPT‑OSS.



We own the **end‑to‑end fine‑tuning platform via Heron** , spanning:



+ Data extraction and isolation

+ Secure training and evaluation workflows

+ Model deployment, migration, and lifecycle manag...

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