1. price

There are many that don’t care about the open-source philosophy, but still support it for this reason. So I’ll start with it though I believe it’s not the most important one. Most open-source software is free. Take a look at OpenOffice.org for example. A great office suit, and it won’t cost you a dime.Or linux: a great alternative to Microsoft Windows. True, people can ask money for their linux version. And if I download a version of the internet, burn it on a CD and install it on someone’s computer, I could ask some money for the costs of the CD and the time I spent installing it or the support I give. But still, you could download and install it yourself for free. That’s like free beer you’re getting here.

2. scalability

This will be important especially for enterprises. If you can cut on the cost, and even get the software for free, there is nothing that prevents you from multiplying everything as far as you see fit. No more additional license costs because the software you just bought only allows you to use one copy on one machine. From now on, you can use as many copies as you like on all the places you like. If your company is growing you don’t need to fear those extra license costs any more. If you dream about extending the installation of the software to another department: open-source makes your dream come true without budget nightmares.

3. security

A hot topic. Take the Firefox versus Internet Explorer debate. That’s open-source versus closed-source. Now tell me, which of the two is safest? Let’s be honest: we know Firefox did have its security problems as well. But anyone can look in the code and go hunting for security issues. And anyone can help to address those security issues once they are found. Closed-source software like Internet Explorer doesn’t have this benefit. therefore security bugs in Firefox are found and fixed faster.

4. develops and improves faster

Free software attracts more users than its non-free counterparts. Especially when the product is as good as that counterpart. therefore open-source software generally attracts more users and receives more and better feedback. This is necessary for improvement.
Also, many open-source projects tend to attract a good deal of programmers who work on the project in their free time. Most open-source projects are not limited by profits and therefore have no limit on developers that can participate.

5. more flexibility

Because the source-code is freely available, anyone who has the knowledge and needs to adjust some part of it can do so. If you need to have software X work on software Y you can take the code, make some adjustments and get them to work together (if they not already do so). Need a feature software X doesn’t have? Add it yourself. This is not possible with most closed-source software and definitely a lot harder when you can’t see the source code.

6. works lifelong

No more worries that one day you won’t be able to read your documents in format Z anymore because this format has become obsolete. If only the format was open-source. You still would be able to make this readable. That is because the open-source license doesn’t prohibit that the knowledge on how exactly you can read it is available to everyone.

7. respect for your hardware’s age

It seems like some companies that sell closed-source software have a secret deal with hardware manufacturers. Every time they upgrade their product you need the need the newest hardware to be able to play with all the new bloat (sometimes called features) that is introduced. Most open-source software projects have respect for hardware and make their software work with as little requirements as possible. Often more alternatives exist where you can choose the one that fits your hardware the most. Linux desktops are an example.

8. more power

As discussed above you can customize open-source software to your needs. A nice advantage this brings is that it becomes more powerful. You don’t need feature A? Take it out and save space and processing time. You need feature B to be more robust? Change it so it comes more robust. You’ll end up, not with what a company thinks you need, but with what you actually need. And that means more power.

9. freedom

Open-source is all about freedom. You, the end user are in control. With closed-source software the company that builds the software is in control. If it decides no longer to implement a feature you need, there’s very little you can do. If it decides that from now on you have to jump through loops to get the software activated, the only thing you can do is jump through loops. With open-source software you are not at the mercy of someone else because you have direct access to the source code. But there’s more freedom than that. “Free software is a matter of the users’ freedom to run, copy, distribute, study, change and improve the software.” (http://www.gnu.org/philosophy/free-sw.html) Think about free as in “free speech”.

10. community support

Which software is more likely to attract a support community? One that is closed-source and makes profit from selling, or an open-source one that shares all it has with its community? People might think there is no support for a free product, but after making the reasoning above you might want to think different. And the proof is out there. I don’t think anyone can count the number of linux support sites that exist, its mailing lists and IRC channels, all there to help people when they have a question. While I think that developing open-source software and at the same time providing paid professional support for it is very interesting, there will always be users spending their free time trying to help people with their knowledge. If you have a problem, it’s very likely someone will have the answer for you.