Popular sites using opensource technologies

Quora uses the Pylons and Comet technologies for its backend and Ubuntu Linux as its operating system with MySQL as its database. It also uses Git and memcached. Quora uses Nginx as a reverse proxy server and HAProxy for load balancing.^{[citation needed]} Quora has developed its own algorithm to rank answers, which works similarly to Google PageRank.^[32] Quora uses Amazon Elastic Compute Cloud technology to host the servers that run its website.^[33][34] In August 2011, Quora switched its infrastructure's Python implementation from CPython to PyPy, to speed response time.