** We are looking for great engineers to drive more growth for Square! ** http://bit.ly/1EwQBSA

Staff Software Engineer / Engineering Manager @ * Payments. Worked on the settlement system, which moves money and verifies bank accounts. * Growth Platform. Managed the engineering team that builds tools for growing Square's business. From August 2013 to Present (2 years 3 months) Research Scientist @ * HipHop for PHP. Led the effort of optimizing the HipHop compiler and runtime system. Improved the efficiency of all the Facebook web servers by 3 times. * Mobile performance. Worked on optimizing Facebook on mobile WebKit and Android platform. Developed tools for profiling and collecting performance data on mobile systems. * Distributed storage system. Worked on the development of a new system that supports efficient data fetching and distributed storage at the Facebook scale. From August 2009 to August 2013 (4 years 1 month) Ph.D. @ From August 2003 to February 2010 (6 years 7 months) Research Intern @ From June 2006 to August 2006 (3 months) Engineering Intern @ From May 2005 to August 2005 (4 months)

Doctor of Philosophy (Ph.D.), Computer Science @ Cornell University From 2003 to 2009 B.E., Computer Science @ Tsinghua University From 1999 to 2003 Xin Qi is skilled in: Algorithms, Distributed Systems, Computer Science, C++, Scalability, Java, Compilers, Database Systems, PHP, Ruby, Databases, Web Services, Mobile Devices, Artificial Intelligence, Android, Web Applications