The Software Engineer Principal is responsible for joining the Enterprise Mobile Reliability Engineering team, providing leadership in the design, development, and end-to-end lifecycle management of consumer mobile applications at enterprise scale. This role will focus on ensuring the reliability, resiliency, and operational excellence of mobile products that millions of users depend on. Collaboration is central: the Software Engineer Principal partners closely with other product and engineering teams to share reliability best practices, address complex technical questions, and encourage robust cross-team connections. They will also actively engage with third-party vendors and the open-source community to drive continuous improvements in stability and resiliency across the mobile application portfolio. Key technical responsibilities include architecting and building reusable code elements, producing architectural diagrams, and developing comprehensive documentation that supports mobile resiliency and effective incident response. The Software Engineer Principal will establish service level objectives specifically crafted for the unique demands of consumer mobile applications, and is deeply involved in configuring, monitoring, performance tuning, and reliability testing of apps in production. As a technical leader, this individual is expected to mentor and develop junior engineers, cultivating expertise in mobile reliability engineering and fostering a culture of operational excellence. Demonstrated experience throughout the complete product lifecycle-from inception through monitoring and incident management-combined with mastery of modern mobile development practices, is essential for success in this role.