A company sells a closed source software product - one that they actively also obfuscate - and market it as "open and flexible". Similarly there is no public issue tracking and when major exploits are discovered they do not openly inform everyone either.

When directly asked about this, they simply ignore the question. This seems like a rather misleading use of the word "open" as they don't seem to reflect any of the values of "open source". But maybe I'm biased because I care too much about open source software and I'm expecting more than I should be from this company based on their marketing material. Is "open software" different from "open source"?

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    I've removed the commentary for the top of this question. If you want to understand the scope of this site better, please ask a question on Meta instead. May 19 '20 at 13:30
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    "Open software" doesn't appear to have any formal definition, so in that respect, yes it's different from open source. May 19 '20 at 14:14
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    Why don't you just name and shame the company in question?
    – JohnEye
    May 20 '20 at 0:07
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    If a program has a plugin, it is open for extension. Giving people access to the source code is quite different, and not necessarily better (e.g. a plugin system allows people to easily share plugins as pieces for assembly, while modifying the source code directly means that either everyone uses the same sources, or things get unwieldy very quickly). "Open" existed long before "open source" - people generally understood what open means, since it's just an English word. It's also used as a marketing blurb, of course. Open source is an actual term, and very specific about what it means.
    – Luaan
    May 20 '20 at 10:00
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    @JohnEye That would invite unproductive shaming.
    – jpaugh
    May 20 '20 at 18:12

The term "open source" has a broad base of speakers who use the term to refer strictly to software licensed under terms in compliance with the Open Source Initiative's Open Source Definition document.

I am unaware of any community of speakers that acknowledges a formal definition for "open software." Broadly, "open" might indicate some ability to integrate with other systems (e.g., having an extensive API might be considered "open" by some speakers) or the ability to be inspected (but source visibility is only one fraction of the OSI's Open Source Definition). However, while "open source" as used above is a binary -- either some license/software meets the OSI's formal definition or not -- the adjective "open" as applied to software is a subjective determination. ("How open is it?" might be answered by "Not very", "somewhat", or "sufficient for my needs" to list a few possibilities.)

If you hear someone talking about "open source" it may be worthwhile to confirm that they are using the term in the well-established OSI-prescribed sense of the term, since (like most language in general) not everyone uses the term in a uniform sense. On the other hand, if you hear someone talking about "open software" it is worthwhile to confirm what they mean at all, since there is no obvious single meaning to attach to the term.

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    This answer is wrong. The concept of open systems being closed source but accessible to the user predates the concept of open source. People were talking about open systems in the 30s - before WW2. A product is open if one can either integrate it with your own work or integrate your work with the product. An example of an open software is Adobe Photoshop - you can write plugins for it and you can write scripts for it making it open
    – slebetman
    May 20 '20 at 13:00
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    @slebetman It's good to know that "open" does have a precise meaning, at least to some folks. OTOH, this answer hedges two ways, so it's actually not wrong. "I am unaware of any community of speakers that acknowledges a formal definition"
    – jpaugh
    May 20 '20 at 18:18
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    @jpaugh I also recently edited this answer somewhat, so slebetman's critique might be less applicable now. (I didn't edit the sentence you quote but did modify the following context.)
    – apsillers
    May 20 '20 at 18:49
  • It is good to have standards. That is why we have so may contradicting ones. May 22 '20 at 23:14

As the other answer says, "open software" is not generally used as a synonym for "open source software".

If I heard a vendor describe their application as "open and flexible", I would generally interpret that as meaning that it provides many hooks for customizing the behavior, but without actually making the source code available. As a result, you're limited to the customization points that they provide.

While this is better than nothing, it's not nearly as good as being able to tailor the internal code of the application. The attitude "We know better than you where you need to customize" is antithetical to the open source mindset.


The concept of an open system in engineering predates the concept of open source by a few decades. The use and popularity of the concept in software development occurred roughly the same time as, if a bit earlier than, open source - with the development and rise of Unix in the 1980s.

An open software is one that can be easily integrated with other software. An example of which is the SWIFT system for bank-to-bank transfer. All banks agree to how it should work and all banks can integrate with it. The fact that you need to pay SWIFT an annual fee to connect to their network does not make them closed.

An example of a closed system is the API banks develop for their own online banking portals - other banks cannot integrate with those APIs easily without working directly with the bank that owns the API.

Other examples of open systems include Adobe Photoshop (anyone can write plugins and scripts for it), Wordpress, the PCIe interface, USB and the MPEG4 media format. Some of which are open source, others are closed source, still others are patented.

In this usage, the concept of open is well defined in industry. People who are new to programming or who didn't grow up in the 80s where almost everything is incompatible with each other may not be familiar with this use of the term open. But throughout the history of computing the term open has been used to promote interoperability.

The are also systems, including software, that can be integrated but is not considered open. The main difference between the two is weather you need permission to integrate said system with yours. Payment is not an issue. If you are required to pay, for example to write apps for iOS, the system is still considered open. What is not open is if the owner of the system can refuse to allow you to integrate the system or integrate with the system or charge you a lot more to allow you to use their system compared to others.

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    This could use some more references. (Perhaps selfishly, as I'd love to read up more on this).
    – T.E.D.
    May 20 '20 at 14:47
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    @T.E.D. - It's hard to google "open" and "software" because of the sheer number of articles about open source. But I found that googling "open system computing" gives good results on the subject. I'm going to modify my answer a bit because it seems that open system became popular in software development around the same time as open source - with the development and rise of unix
    – slebetman
    May 21 '20 at 10:48

"Open" and "flexible" are meaningless marketing terms.

It's like saying that a breakfast cereal is "natural" or "nutritious". There are no standard definitions of "natural" or "nutritious".

Your hand can be described as "open and flexible", but it's definitely not open-source. (Technically, it can even be described as "natural and nutritious", but let's not go there.)

Often, "open" just implies that software has accessible API's or is able to import/export to a variety of data formats. But it doesn't even have to mean that much.

I recommend completely ignoring such vague marketing terms, and questioning the motives and integrity of any company using such language.

To be considered open-source, the developer must publish the current and complete source code in a location accessible to all users.

  • Actually, the source code doesn't have to be published in a publicly accessible location for a project to be open-source. Even with a copyleft license like the GPL, the code just has to be available to the users of the project, which can be quite restricted. May 22 '20 at 6:12
  • @BartvanIngenSchenau Thank you for the clarification. I've updated my answer accordingly. May 22 '20 at 12:03

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