RESEARCH ARTICLE Quantifying the web browser ecosystem Sela Ferdman 1 , Einat Minkov 2 , Ron Bekkerman 3 *, David Gefen 4 1 Department of Computer Science, University of Haifa, Haifa, Israel, 2 Department of Information Systems, University of Haifa, Haifa, Israel, 3 Department of Information and Knowledge Management, University of Haifa, Haifa, Israel, 4 LeBow College of Business, Drexel University, Philadelphia, PA, United States of America * ronb@univ.haifa.ac.il Abstract Contrary to the assumption that web browsers are designed to support the user, an exami- nation of a 900,000 distinct PCs shows that web browsers comprise a complex ecosystem with millions of addons collaborating and competing with each other. It is possible for addons to “sneak in” through third party installations or to get “kicked out” by their competitors with- out user involvement. This study examines that ecosystem quantitatively by constructing a large-scale graph with nodes corresponding to users, addons, and words (terms) that describe addon functionality. Analyzing addon interactions at user level using the Personal- ized PageRank (PPR) random walk measure shows that the graph demonstrates ecological resilience. Adapting the PPR model to analyzing the browser ecosystem at the level of addon manufacturer, the study shows that some addon companies are in symbiosis and others clash with each other as shown by analyzing the behavior of 18 prominent addon manufacturers. Results may herald insight on how other evolving internet ecosystems may behave, and suggest a methodology for measuring this behavior. Specifically, applying such a methodology could transform the addon market. Introduction Web browsers have become a major component of the routine human-computer interaction, with some operating systems based entirely on browsers (e.g., ChromeOS by Google [1]). Browser extensions, also known as addons, are computer programs that (as the name suggests) extend, improve, and personalize browser capabilities. More than 750 million addons were downloaded and installed by Google Chrome browser users as of June 2012 [2]. Some exam- ples of addons include an extension that allows visually impaired users to access the content of bar charts on the Web [3], an extension that addresses users’ security concerns by seamlessly producing a unique password for each website the user accesses [4]. Internet software companies are very interested in installing their addons, and particularly toolbars, on users’ machines. Toolbars are GUI widgets that typically reside in the upper part of the browser’s window, extending the browser’s functionality. Toolbars can collect informa- tion about the browsing history of the user (e.g., Yahoo! Toolbar [5]) and can redirect user search activity to a specific search portal (e.g. MyWebSearch.com). Crucially, the company PLOS ONE | https://doi.org/10.1371/journal.pone.0179281 June 23, 2017 1 / 27 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Ferdman S, Minkov E, Bekkerman R, Gefen D (2017) Quantifying the web browser ecosystem. PLoS ONE 12(6): e0179281. https:// doi.org/10.1371/journal.pone.0179281 Editor: Hussein Suleman, University of Cape Town, SOUTH AFRICA Received: December 15, 2016 Accepted: May 11, 2017 Published: June 23, 2017 Copyright: © 2017 Ferdman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are hosted at figshare at the following URL: https://doi. org/10.6084/m9.figshare.5063332.v1. Funding: The authors received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist.