I like to make things, usually on the web, that make life easier and world a better place. I've worked with the entire web stack (i.e., Hadoop/Pig → SQL → web framework (rails/sinatra/django/express) → js/css/html). I've worked on projects exclusively using Pig/Hadoop in the backend, as well as projects using javascript/css on the front. Currently, I like JavaScript a lot more, and firmly believe in Attwood's Law. I've also built things in Java, but am a bigger fan of dynamic languages. Always open to discuss technology, startups, economy, and the like. Specialties: - JavaScript: node.js, coffeescript, JQuery, socket.io, Faye, Backbone, Ember.js, d3 - Ruby: Rails, Sinatra - Web: HTML5, CSS (LESS, SASS) - Java: Spring, Hibernate - Others (significant experience): Swift, PHP, Perl, Python (Flask), SQL, Lisp, C++ - Distributed: Apache Hadoop, Pig - Design: Photoshop, InDesign, Flash Builder Other interests: AI, mobile applications

Software Engineer @ From April 2015 to Present (7 months) San Francisco Bay AreaSenior Software Engineer @ I worked on Twitter's advertising platform with the revenue team. My role was full-stack (MySQL/Scala/Rails/JavaScript) with a greater focus on the front-end. I drove JavaScript development of many features for advertisers, many of which had revenue impact of more than $10M/yr. In particular, I led the front-end development of the following projects: - redesign of Twitter's Ads center and dashboards - redesign and re-architecture of advertising campaign creation flow - interest and user targeting on Twitter - campaign recommendations - mobile app promotion on Twitter I also authored self-contained UI components that became standard across Twitter's business-facing interfaces. Examples include a tree-based typeahead search widget and a sheet-based modal popup. From June 2012 to April 2015 (2 years 11 months) San Francisco Bay AreaSoftware Engineer Intern, Revenue @ Worked with the front-end team: - integrated New Tweet box into advertising platform, allowing advertisers to tweet directly from ads.twitter.com - built prototype dashboard for tweet and timeline activity, written in JavaScript with MVC architecture From June 2011 to September 2011 (4 months) San Francisco Bay AreaData analysis intern @ Migrated traditional Perl-based data analysis tools to MapReduce. Wrote the initial Hadoop/Pig implementation of data analysis and aggregation tools for the Merchant Recommender feature. Performed some automated data analysis and processing using Perl and R. From January 2011 to May 2011 (5 months) Greater New York City AreaSummer Analyst @ Implemented composite data model for predicate validators of rules written in BlackRock Query Language (BQL), used for the validation of posted trades and orders. Supported predicates from both Java Spring beans and from database. Developed novel object-relational parser of Comma Separated Values (CSV) files that interprets flat files as object trees based on column header matching with customizable XML schema configuration files. Added support for recursive parsing of infinite number of levels and adapted the parsing engine for generic classes. Used to parse large batches of posted trades and orders. Developed prototype Quick Confirm plug-in using Java Swing for trade and order confirmation in BlackRock’s trade monitoring system, Dashboard, in accordance with internal UI standards. From June 2010 to August 2010 (3 months) Greater New York City AreaSoftware Developer intern @ - Developed automation scripts for product pre-testing in AutoHotKey - Developed batch-testing automation program in Tcl and Perl - Worked in Production Engineering team and analyzed benefits of automation and areas of improvement From June 2009 to August 2009 (3 months) Interpreter @ Worked as an interpreter for Chinese Oracle Calligraphy Exhibition, sponsored by The Permanent Mission of the People's Republic of China to the United Nations. Provided guest translation services between Chinese and English. From January 2009 to January 2009 (1 month) Software Developer @ - Developed automation tools for LED Panel testing - Automated burn-in testing of RuggedSwitch - Updated RuggedCom FinalTest in accordance to new releases of operating systems for RuggedSwitch - Automated wireless calibration of RuggedSwitch using Tcl Expect From June 2008 to August 2008 (3 months)

BS, Computer Science, Economics, 3.9 @ Columbia University in the City of New York From 2008 to 2012 Yufei L. is skilled in: Perl, Ruby on Rails, Python, Hadoop, Java, JavaScript, Ruby, jQuery, Node.js, Sinatra, Apache Pig