Microsoft Security is seeking a Senior Software Engineer to join their Microsoft Entra group, which serves over a billion active users through Microsoft Entra ID and Microsoft Account services. As part of the Core Authentication team, you'll be responsible for the authentication service that secures access to applications and services across Microsoft's ecosystem. The role offers an opportunity to work on highly scalable distributed systems serving billions of users monthly, requiring deep technical expertise and a live site-first mentality. You'll be instrumental in building and shaping the team's engineering culture while working in a collaborative hybrid environment. The position involves working with core services that are fundamental to almost every Microsoft product and platform including Office, Xbox, HoloLens, and Azure. The team focuses on enterprise and customer identity and access management (CIAM) spaces, requiring expertise in building fault-tolerant, geo-distributed services. Microsoft's culture emphasizes a growth mindset, excellence, and empowering teams to bring their best each day, contributing to innovations that impact billions of lives worldwide. The role combines technical leadership, hands-on development, and collaboration with teams across multiple geographies.