Why Open Source Software / Free Software (OSS/FS)? Look at the Numbers! David A. Wheeler [email protected] Revised as of September 8, 2003 This paper provides quantitative data that, in many cases, using open source software / free software is a reasonable or even superior approach to using their proprietary competition according to various measures. This paper’s goal is to show that you should consider using OSS/FS when acquiring software. This paper examines market share, reliability, performance, scalability, security, and total cost of ownership. It also has sections on non-quantitative issues, unnecessary fears, OSS/FS on the desktop, usage reports, other sites providing related information, and ends with some conclusions. An appendix gives more background information about OSS/FS. You can view this paper at http://www.dwheeler.com/oss_fs_why.html (HTML format). Palm PDA users can view it in Plucker format (you will also need Plucker to read it). A short briefing based on this paper is also available in PDF and Open Office Impress formats (for the latter, use Open Office Impress). Old archived copies and a list of changes are also available. 1. Introduction Open Source Software / Free Software (OSS/FS) has risen to great prominence. Briefly, OSS/FS programs are programs whose licenses give users the freedom to run the program for any purpose, to study and modify the program, and to redistribute copies of either the original or modified program (without having to pay royalties to previous developers). This goal of this paper is to show that you should consider using OSS/FS when you’re looking for software, based on quantitative measures. Some sites provide a few anecdotes on why you should use OSS/FS, but for many that’s not enough information to justify using OSS/FS. Instead, this paper emphasizes quantitative measures (such as experiments and market studies) on why using OSS/FS products is, in many circumstances, a reasonable or even superior approach. I should note that while I find much to like about OSS/FS, I’m not a rabid advocate; I use both proprietary and OSS/FS products myself. Vendors of proprietary products often work hard to find numbers to support their claims; this page From www.dwheeler.com/oss_fs_why.html 1 10 September 2003 provides a useful antidote of hard figures to aid in comparing proprietary products to OSS/FS. Note that this paper’s goal is not to show that all OSS/FS is better than all proprietary software. Certainly, there are many who believe this is true from ethical, moral, or social grounds. However, no numbers could prove such broad statements. Instead, I’ll simply compare commonly-used OSS/FS software with commonly-used proprietary software, to show that at least in certain situations and by certain measures, some OSS/FS software is at least as good or better than its proprietary competition. Of course, some OSS/FS software is technically poor, just as some proprietary software is technically poor, and even very good software may not fit your specific needs. But although most people understand the need to compare proprietary products before using them, many people fail to even consider OSS/FS products. This paper is intended to explain why acquirers should consider OSS/FS alternatives. This paper doesn’t examine transition approaches, but it’s worth noting that organizations can transition to OSS/FS in part or in stages, which for many is a more practical transition approach. I’ll emphasize the operating system (OS) known as GNU/Linux (which many abbreviate as “Linux”) and the Apache web server, since these are some of the most visible OSS/FS projects. I’ll also primarily compare OSS/FS software to Microsoft’s products (such as Windows and IIS), since Windows has a significant market share and Microsoft is one of proprietary software’s strongest proponents. I’ll mention Unix systems in passing as well, though the situation with Unix is more complex; today’s Unix systems include many OSS/FS components or software primarily derived from OSS/FS components. Thus, comparing proprietary Unix systems to OSS/FS systems (when examined as whole systems) is often not as clear-cut. I use the term “Unix-like” to mean systems intentionally similar to Unix; both Unix and GNU/Linux are “Unix-like” systems. The most recent Apple Macintosh OS (MacOS OS X) presents the same kind of complications; older versions of MacOS were wholly proprietary, but Apple’s OS has been redesigned so that it’s now based on a Unix system with substantial contributions from OSS/FS programs. Indeed, Apple is now openly encouraging collaboration with OSS/FS developers. I include data over a series of years, not just the past year; all relevant data should be considered when making a decision, instead of arbitrarily ignoring older data, and the older data shows that OSS/FS has a history of many positive traits. You can get a more detailed explanation of the terms “open source software” and “Free Software”, as well as related information, from the appendix and my list of Open Source Software / Free Software (OSS/FS) references at http://www.dwheeler.com/oss_fs_refs.html. Note that those who use the term “open source software” tend to emphasize technical advantages of such software (such as better reliability and security), while those who use the term “Free Software” tend to emphasize freedom from control by another and/or ethical issues. The opposite of OSS/FS is “closed” or “proprietary” software. Software for From www.dwheeler.com/oss_fs_why.html 2 10 September 2003 which the source code that can be viewed, but cannot modified and redistributed without further limitation (e.g., “source viewable” or “open box” software, including “shared source” and “community” licenses), are not considered here since they don’t meet the definition of OSS/FS. Many OSS/FS programs are commercial programs, so don’t make the mistake of thinking OSS/FS is equivalent to “non-commercial” software (indeed, any article making this mistake should be ignored since it is obviously poorly researched). Almost no OSS/FS programs are in the “public domain” (which has a specific legal meaning), so avoid that term as well. Other alternative terms for OSS/FS software include “libre software” (where libre means free as in freedom), free-libre and open- source software (FLOS software or FLOSS), open source / Free Software (OS/FS), free / open source software (FOSS), open-source software (indeed, “open-source” is often used as a general adjective), “freed software,” and even “public service software” (since often these software projects are designed to serve the public at large). OSS/FS is not “freeware”; freeware is usually defined as proprietary software given away without cost, and does not provide any right to examine, modify, or redistribute the source code. The most popular OSS/FS license is the General Public License (GPL); all software released under the GPL is OSS/FS, but not all OSS/FS software uses the GPL; nevertheless, some people do inaccurately use the term “GPL software” when they mean OSS/FS software. This is a large paper, with many acronyms. A few of the most common acryonyms are: Acronym Meaning GNU GNU’s Not Unix (a project to create an OSS/FS operating system) GPL General Public License (the most common OSS/FS license) OS, OSes Operating System, Operating Systems OSS/FS Open Source Software/Free Software Below is data discussing market share, reliability, performance, scalability, security, and total cost of ownership. I close with a brief discussion of non- quantitative issues, unnecessary fears, OSS/FS on the desktop, usage reports, other sites providing related information, and conclusions. An appendix gives more background information about OSS/FS (definitions, motivations of developers, history, and license types). From www.dwheeler.com/oss_fs_why.html 3 10 September 2003 2. Market Share Many people think that a product is only a winner if it has significant market share. This is lemming-like, but there’s some rationale for this: products with big market shares get applications, trained users, and momentum that reduces future risk. Some writers argue against OSS/FS or GNU/Linux as “not being mainstream”, but if their use is widespread then such statements reflect the past, not the present. There’s excellent evidence that OSS/FS has significant market share in numerous markets: 1. The most popular web server has always been OSS/FS since such data have been collected. For example, Apache is currently the #1 web server with over twice the market share of its next-ranked competitor. Netcraft’s statistics on web servers have consistently shown Apache (an OSS/FS web server) dominating the public Internet web server market ever since Apache grew into the #1 web server in April 1996. Before that time, the NCSA web server (Apache’s ancestor) dominated the web from August 1995 through March 1996 - and it is also OSS/FS. Since 2000, Netcraft has been trying to separately count only “active” web sites. The problem is that many web sites have been created that are simply “placeholder” sites (i.e., their domain names have been reserved but they are not being used); such sites are termed “inactive.” Netcraft’s count of only the active sites is a more relevant figure than counting all web sites, since the count of active sites shows the web server selected by those who choose to actually develop a web site. When counting active sites, Apache very well; in September 2002, Apache had 66.04% of the web server market, Microsoft had 24.18%, iPlanet had 1.57%, and Zeus had 1.34%.