Translations available: Czech | French | Japanese | Spanish Why Open Source Software / Free Software (OSS/FS, FLOSS, or FOSS)? Look at the Numbers! David A. Wheeler http://www.dwheeler.com/contactme.html Revised as of July 18, 2015 This paper (and its supporting database) provides quantitative data that, in many cases, using open source software / free software (abbreviated as OSS/FS, FLOSS, or FOSS) 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 popularity, 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, governments and OSS/FS, 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). A short presentation (briefing) based on this paper is also available. Palm PDA users may wish to use Plucker to view this longer report. Old archived copies and a list of changes are also available. 1. Introduction Open Source Software / Free Software (aka OSS/FS), also described as Free/Libre and Open Source Software (FLOSS), has risen to great prominence. Briefly, FLOSS 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). The goal of this paper is to convince you to consider using FLOSS when you’re looking for software, using quantitive measures. Some sites provide a few anecdotes on why you should use FLOSS, but for many that’s not enough information to justify using FLOSS. Instead, this paper emphasizes quantitative measures (such as experiments and market studies) to justify why using FLOSS products is in many circumstances a reasonable or even superior approach. I should note that while I find much to like about FLOSS, I’m not a rabid advocate; I use both proprietary and FLOSS products myself. Vendors of proprietary products often work hard to find numbers to support their claims; this page provides a useful antidote of hard figures to aid in comparing proprietary products to FLOSS. Others have come to the same conclusions, for example, Forrester Research concluded in September 2006 that “Firms should consider open source options for mission-critical applications”. I believe that this paper has met its goal; others seem to think so too. The 2004 report of the California Performance Review, a report from the state of California, urges that “the state should more extensively consider use of open source software”, and specifically references this paper. A review at the Canadian Open Source Education and Research (CanOpenER) site stated “This is an excellent look at the some of the reasons why any [organization] should consider the use of [FLOSS]... [it] does a wonderful job of bringing the facts and figures of real usage comparisons and how the figures are arrived at. No FUD or paid for industry reports here, just the facts”. This paper been referenced by many other works, too. It’s my hope that you’ll find it useful as well. The following subsections describe the paper’s scope, challenges in creating it, the paper’s terminology, and the bigger picture. This is followed by a description of the rest of the paper’s organization (listing the sections such as popularity, reliability, performance, scalability, security, and total cost of ownership). Those who find this paper interesting may also be interested in the other documents available on David A. Wheeler’s personal home page. A short presentation (briefing) based on this paper is also available. This paper has become long, there is now a supporting database of OSS/FS (FLOSS) quantitative studies that you may find easier to use. You may also be interested in the discussion group for quantitative numbers about free / libre / open source software. 1.1 Scope As noted above, the goal of this paper is to convince you to consider using FLOSS when you’re looking for software, using quantitive measures. Note that this paper’s goal is not to show that all FLOSS is better than all proprietary software. Certainly, there are many who believe this is true from ethical, moral, or social grounds. It’s true that FLOSS users have fundamental control and flexibility advantages, since they can modify and maintain their own software to their liking. And some countries perceive advantages to not being dependent on a sole-source company based in another country. However, no numbers could prove the broad claim that FLOSS is always “better” (indeed you cannot reasonably use the term “better” until you determine what you mean by it). Instead, I’ll simply compare commonly-used FLOSS software with commonly-used proprietary software, to show that at least in certain situations and by certain measures, some FLOSS software is at least as good or better than its proprietary competition. Of course, some FLOSS software is technically poor, just as some proprietary software is technically poor. And remember -- 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 FLOSS products, or they create policies that unnecessarily inhibit their use; those are errors this paper tries to correct. This paper doesn’t describe how to evaluate particular FLOSS programs; a companion paper describes how to evaluate FLOSS programs. This paper also doesn’t explain how an organization would transition to an FLOSS approach if one is selected. Other documents cover transition issues, such as The Interchange of Data between Administrations (IDA) Open Source Migration Guidelines (November 2003) and the German KBSt’s Open Source Migration Guide (July 2003) (though both are somewhat dated). Organizations can transition to FLOSS 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”), the Apache web server, the Mozilla Firefox web browser, and the OpenOffice.org office suite, since these are some of the most visible FLOSS projects. I’ll also primarily compare FLOSS software to Microsoft’s products (such as Windows and IIS), since Microsoft Windows is widely used and Microsoft is one of proprietary software’s strongest proponents. Note, however, that even Microsoft makes and uses FLOSS themselves (they have even sold software using the GNU GPL license, as discussed below). I’ll mention Unix systems as well, though the situation with Unix is more complex; today’s Unix systems include many FLOSS components or software primarily derived from FLOSS components. Thus, comparing proprietary Unix systems to FLOSS systems (when examined as whole systems) is often not as clear-cut. This paper uses 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 FLOSS programs. Indeed, Apple is now openly encouraging collaboration with FLOSS developers. 1.2 Challenges It’s a challenge to write any paper like this; measuring anything is always difficult, for example. Most of these figures are from other works, and it was difficult to find many of them. But there are some special challenges that you should be aware of: legal problems in publishing data, the reluctance of many FLOSS users to publicly admit it (for fear of retribution), and dubious studies (typically those funded by a product vendor). Many proprietary software product licenses include clauses that forbid public criticism of the product without the vendor’s permission. Obviously, there’s no reason that such permission would be granted if a review is negative -- such vendors can ensure that any negative comments are reduced and that harsh critiques, regardless of their truth, are never published. This significantly reduces the amount of information available for unbiased comparisons. Reviewers may choose to change their report so it can be published (omitting important negative information), or not report at all -- in fact, they might not even start the evaluation. Some laws, such as UCITA (a law in Maryland and Virginia), specifically enforce these clauses forbidding free speech, and in many other locations the law is unclear -- making researchers bear substantial legal risk that these clauses might be enforced. These legal risks have a chilling effect on researchers, and thus makes it much harder for customers to receive complete unbiased information. This is not merely a theoretical problem; these license clauses have already prevented some public critique, e.g., Cambridge researchers reported that they were forbidden to publish some of their benchmarked results of VMWare ESX Server and Connectix/Microsoft Virtual PC. Oracle has had such clauses for years. Hopefully these unwarranted restraints of free speech will be removed in the future. But in spite of these legal tactics to prevent disclosure of unbiased data, there is still some publicly available data, as this paper shows. Another problem is that many users of FLOSS are reluctant to admit it. ZDNet UK’s November 25, 2005 article “Why open source projects are not publicised” by Ingrid Marson examines this. For example, it notes that many are afraid of retribution.