Servus | Benvingut

Dr. Josep M. Pujol
Jack of all trades, master of none.

About Me

Always trying to solve problems, sometimes successfully.

What I enjoy the most if to create and to experiment. Be it on paper or by building next to production prototypes. Guilty of charge of reinventing the wheel ocasionally, but never the exact same wheel. Lucky enough to have worked in different research labs and start-ups that gave me the change to pursue my interests and to acquire new ones. Always pragmatic.

Born in Solsona in 1977. Lived all around the world: Barcelona, Groningen, Rome, San Francisco, Ann Arbor, M√ľnchen and since 2021 in Andorra.

Brave — Chief of Search
2021 - date

Leading the Brave Search engine, independent and private search engine. There is no freedom without real choice. Check it out at

Cliqz — Chief Scientist
2014 - 2021

Led the team building Cliqz's full-fledged search-engine and Cliqz privacy feature. Creator of the Human Web privacy-preserving data collection. Helping in any way possible to make Cliqz great ambitions to become a reality.

Sadly Cliqz effort was shut-down in early 2020, but the core search and data was maintained as a spin-off called Tailcat, which was later acquired by Brave in February 2021. — Chief Technical Officer 2011 - 2013
Advisor to 3scale since foundation, joined full-time in 2011 as CTO. Responsible for both product and backend production systems. 3scale was acquired by Redhat in 2016.
Telefonica — Research Scientist 2009 - 2011
Research Scientist at Telefonica I+D focused mostly on recommender systems, distributed systems, scalability and networking. The scientific group at Telefonica was a great Industry lab with many great researchers. During my time at Telefonica I participated in more than 15 papers in top-tier conferences and got 3 patents granted.
University of Michigan — Postdoc 2006 - 2009
Joint postdoc at the Center for the Study of Complex Systems and at the Public Health Epidemiology Department. There I worked mostly on dose response models and routes of transmission for influenza. For public safety reasons I was prevented to carry out any type of field study .
PhD on Computer Science and Artificial Intelligence by the Polytechnic University of Catalonia. Thesis titled Structure in Artificial Societies ; studying how the structure of social networks affect the emegerge of complex behaviors such as coordination and cooperation. During my PhD I also worked in different EU-funded projects related to Multi-agent Systems such as Agentcities.
Selected Publications

The full list of publications is available at Google Scholar (missing papers available upon demand).

Tracking the Trackers ACM/WWW 2016
Network and Systems
The Little Engine(s) that Could: Scaling Online Social Networks ACM/SIGCOMM 2010
Fair Routing in Delay Tolerant Networks IEEE/INFOCOMM 2009
Monitoring the Bittorrent Monitors: A bird's eye view PAM 2009
Recommender Systems
The Wisdom of the Few: A Collaborative Filtering Approach Based on Expert Opinions from the Web ACM/SIGIR 2009
Rate it again: increasing recommendation accuracy by user re-rating ACM/RecSys 2009
I like It... I like It Not: Measuring Users Ratings Noise in Recommender Systems UMAP 2009
Epidimeology / Biology
Informing Optimal Environmental Influenza Interventions: How the Host, Agent, and Environment Alter Dominant Routes of Transmission PLoS Computational Biology 2010
The Effect of Ongoing Exposure Dynamics in Dose Response Relationships PLoS Computational Biology 2009
Clustering Algorithm for Determining Community Structure in Large Networks Physical Review E 2007
Extracting Reputation in Multi Agent System by means of Social Network Topology AAMAS 2002
Social features of online networks: The strength of intermediary ties in online social media PLoS One 2012
How can social networks ever become complex? Modelling the emergence of complex networks from local social exchanges JASSS 2005
The role of clustering on the emergence of efficient social conventions IJCAI 2005
Method for Efficient Partition and Replication of Social-Based Applications Patent #US20110276649 2010
Method for Balancing Loads in Mobile Wireless Ad-hoc Networks Patent #US20110261692 2010
Recommender System Based on Expert Opinions Patent #US20110137726 2009
Programm Comitte
Served in the programm committee at WAW 2011, SIGIR 2010, IDAR/SIGMON 2010, CERI 2010, COPS 2009. Coorganizing the Social Mobile Web Workshop (SMW), colocated with SocialCom 2009, MobileHCI 2010.
Start-up advisor at HackFwd, an European-based start-up incubator.