ReddIt

MemeTracker site http://reddit.com/

Reddit was founded in June 2005 [19] by Steve Huffman and Alexis Ohanian in Medford MA, both 22-year-old graduates of the University of Virginia.[20] It received its initial funding from Y-Combinator. The team expanded to include Christopher Slowe in 2005. Aaron Swartz joined in late January 2006 as part of the company's merger with Swartz's InfoGami.[21] Conde Nast Publications, owner of Wired Com, acquired Reddit on October 31, 2006.[22] Shortly thereafter, Swartz was fired... On September 6, 2011, Reddit became operationally independent of Conde Nast, now operating as a separate subsidiary of its parent company, AdvancePublications.... In October 2014, Reddit raised $50 million in a funding round led by Sam Altman and including investors Marc Andreessen, Peter Thiel, Ron Conway, Snoop Dogg, and Jared Leto.[9] Their investment valued the company at $500 million then.[10][11] In July 2017, Reddit raised $200 million for a $1.8 billion valuation, with Advance Publications remaining the majority stakeholder.[12] In February 2019, a $300 million funding round led by Tencent brought the company's valuation to $3 billion.[13] http://en.wikipedia.org/wiki/Reddit

Uses more personalized Collaborative Filtering than the other ones?

A clone written in Flask?