Jonathan “Peli” de Halleux is actively working on TouchDevelop and Code Hunt. In the past, Peli worked on Moles (shipped as Fakes in Visual Studio 2012), rise4fun, Pex and Code Digger. Every morning, Peli teaches mobile computer science at his local high school.

Peli joined the Foundations for Software Engineering in October 2006. Peli worked in the CLR as a SDET in charge of the Just In Time compiler (2004-2006). Before joining Microsoft, Peli earned a PhD in Applied Mathematics from the Catholic University of Louvain (2000-2004).


Code Hunt Community

Established: July 17, 2015

Code Hunt is a serious educational game. The Code Hunt community is interested in all aspects of research and development around the game, including analysis of the data and development of the platform. Join the Community Get updates. Tell us…

Code Hunt

Established: February 4, 2015

Code Hunt is a serious gaming platform for coding contests and practicing programming skills. It is based on the symbolic white box execution engine, Pex. Code Hunt is unique as an online coding platform in that each puzzle is presented…


Established: July 20, 2011

Create apps everywhere on all your devices! For Windows Phone and the web. In the TouchDevelop programming environment you write scripts by tapping on the screen. You do not need a separate PC or keyboard. Scripts can perform various tasks…


Established: March 15, 2011

This project has been renamed to TouchDevelop. Please visit the new Microsoft Research project website and see what scripts people write on touchdevelop.com.   Videos Watch the Channel 9 video to learn how to Script Your Phone ON Your…













Peli teaches computer science at Rainier Beach High School every morning, as part of the TEALS program. Peli had the chance to be featured in an article of the New York Times about TEALS. In collaboration with Michael Braun at Rainier Beach, Peli co-organized AppDay, a high school event where 900 students enjoyed coding for a day. Read the GeekWire articles about this program from 2014 and 2013.


Geek of the Week

Twice, Peli was selected as geek of the week. You can read about it here and here.


Old Personal Projects

  • Creator of MbUnit, an extensible unit test framework for .Net that integrated features such as combinatorial testing.
  • QuickGraph, a library for graph data structures and algorithm in .NET,
  • Reflector Addin’s, a set of specialized modules for Reflector that range from type graph, code complexity, code review, treemap of types, statement graphs, an attempt at automatic test case generation from a method basic block graph, etc..
  • Stuff, ranging from Ant Colony Optimization, autonomous behaviors, a framework for performance tests or an attempt at literate documentation in C#.