The base system (Xtreme Online Judge) development began in 2006 under the "Xtreme Initiative", mainly composed by students and teachers of the 8th faculty of the University of Informatics Sciences (UCI): Tomas Orlando Junco Vazquez, Enrique Jose Altuna Castillo, Jorge Amado Soria Ramirez, Jose Ernesto Lara Rodriguez, Raciel Yera Toledo and Leandro Gonzalez Vallejo.

After the UCI joined the ACM-ICPC (ACM-Association for Computing Machinery, ICPC-International Collegiate Programming Contest) movement and led the creation of the Caribbean Community of the ACM-ICPC, the Xtreme Online Judge was selected to be published online as the COJ v1.0, and other people joined the small but inspired development team (Yonny Mondelo Hernandez and Dovier Antonio Ripoll Mendez). The COJ is available on the Internet since June 5, 2010.

In October 2011 the base system was replaced by another that was reprogrammed from scratch (for almost one year) by two young students of the UCI (Juan Carlos Lobaina Guzman and Jorge Luis Roque Alvarez). Since then the working teams and methods have been improved to get a better system.


Provide a space where people of the world can:

  • exchange experiences and knowledge;
  • test, improve and share skills on problem-solving, computer programming and teamwork;
  • train to participate in programming competitions (ACM-ICPC, IOI, TopCoder, and others).


The system automatically compiles and executes the code sent by the user (solution to a problem). The submitted source code will be tested with some restrictions, including the execution time, the memory usage, the size of the source code, the security and others. The output of the code will be captured by the system and compared to the correct output provided by the problem setter. The user will get Accepted (as judgment or verdict) if all tests applied to their source code seem to be OK. Otherwise, the user will get a rejection response.



The COJ Project requires the support of many people, each one with their own areas of responsibility. Below is a listing with the current members of the CDEVT:

  • Yonny Mondelo Hernández (UCI, Cuba).
  • Dovier Antonio Ripoll Méndez (UCI, Cuba).
  • Yunier Broche Guevara (UCI, Cuba).
  • Frank Arteaga Salgado (ULT, Cuba).
  • Amaro Francisco Benjamim Buta (ISUTIC, Angola).
  • Moisés Daniel Gonga (ISUTIC, Angola).

Former members of our team:

  • Tomás Orlando Junco Vázquez (UCI, Cuba).
  • Jorge Amado Soria Ramirez (UCI, Cuba).
  • Eddy Roberto Morales Pérez (UCI, Cuba).
  • Leandro González Vallejo (UCI, Cuba).
  • Jorge Luis Roque Alvarez (UCI, Cuba).
  • Nersa Doraines Acosta Labrada (UCI, Cuba).
  • Juan Carlos Lobaina Guzmán (UCI, Cuba).
  • José Ernesto Lara Rodríguez (UCI, Cuba).
  • Michael Horta Fleitas (UCI, Cuba).
  • Nellis Margarita Cabrera Mallea (UCI, Cuba).
  • Frank Yurell Villafranca (UCI, Cuba).
  • Alain Félix Plana Botello(UCI, Cuba).
  • Yelaine Sánchez Oliü (UCI, Cuba).
  • Alison Muñoz Capote (UCI, Cuba).
  • Jorge Amado Hernández Betancourt (UCI, Cuba).


Please, contact us:

  • if you are planning a programming competition (e.g., to select the best teams or contestants for an international contest). We can host your contest in the COJ.
  • if you have an exercise with its description and the test data files (collected or created by yourself). We can publish your problem in our set.
  • if you want to collaborate on the development and improvement of the COJ. You are welcome to join us to change "our world" by a better one.

Can you collaborate in another way? Please, tell us!