Jonathan Klein, Software Developer in Boston, MA, United States
Jonathan Klein

Software Developer in Boston, MA, United States

Member since May 22, 2015
Jonathan is a Lead Engineer at, where he focuses on solving both front-end and back-end issues. He started the Boston Web Performance Meetup Group, and he contributes to a few open source projects, including the HTTPArchive, WebPagetest, and CSSLint. He is also the co-creator of Hound and wpt-script, two open source projects built at Etsy.
Jonathan is now available for hire


    AngularJS, Apache, Ruby on Rails (RoR)
  • Etsy
    MySQL, React, JavaScript, Git, Chef, PHP
  • Wayfair
    SQL, JavaScript, CSS, ASP, Subversion (SVN), PHP



Boston, MA, United States



Preferred Environment

Sublime Text 3, Vagrant, GitHub

The most amazing...

...tool I've open sourced is Hound, a code search tool built at Etsy.


  • Lead Engineer

    2015 - PRESENT
    • Focused on front-end architecture and building a strong engineering team.
    Technologies: AngularJS, Apache, Ruby on Rails (RoR)
  • Senior Software Engineer

    2012 - 2015
    • Wrote public-facing site performance reports on Etsy’s “Code as Craft” blog, communicating quarterly load time metrics for
    • Deployed and managed a custom WebPagetest instance on Amazon EC2 cloud servers, which was used to monitor site performance.
    • Open-sourced wpt-script, a WebPagetest client that makes it easy to automatically run tests and gather data from WebPagetest.
    • Open-sourced Hound, a code search tool which became Etsy’s third most popular open source project within one month of launch.
    • Conducted performance audits across and built tooling to make regressions easier to identify and fix.
    Technologies: MySQL, React, JavaScript, Git, Chef, PHP
  • Senior Software Engineer

    2008 - 2012
    • Received 2009 “Founder’s Award for Innovation,” given to one employee each year hand-picked by the company founders out of 500+ candidates for outstanding contributions to the business.
    • Promoted three times in less than four years, which was dramatically faster than peers.
    • Led a team of five internal engineers and four remote contractors to rewrite's code base using PHP, incorporating site design and brand overhaul.
    • Trained and led a four-person CSS team during a redesign of all 200+ CSN Stores websites in 2009, establishing company-wide coding conventions and best practices.
    • Built new features for the customer-facing websites as well as back-end tools to make it easier for our marketing team to make data changes.
    Technologies: SQL, JavaScript, CSS, ASP, Subversion (SVN), PHP



  • Languages

    PHP, HTML, CSS, JavaScript, SQL, Python
  • Frameworks

    Ruby on Rails (RoR), Laravel, ASP, AngularJS
  • Storage

    Memcached, PostgreSQL, MySQL
  • Other

    Front-end Development, Software Development
  • Libraries/APIs

    Node.js, jQuery, React
  • Tools

    Subversion (SVN), Sublime Text 3, Packer, Vagrant, Chef, Git, Apache, GitHub
  • Paradigms

    Agile Software Development
  • Platforms

    Amazon EC2


  • Bachelor of Science Degree in Astronomy and Physics
    2004 - 2008
    Haverford College - Haverford, PA

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