The past few years were a much simpler time for app developers.

If you wanted to build a mobile app, then you built an iPhone app. If you cared about larger resolutions, then you took your app and made it compatible for iPads and Retina displays. And maybe after all that was done, you’d peer into the Android ecosystem and decide if you could be bothered to port the app.

In the middle of all this, there was another OS called Windows Phone 7, but it was largely ignored by all but the firmest fans of Microsoft and Nokia.

At the end of last year though, Windows Phone 8 appeared, and people were far more curious about this new platform than they had been about its predecessor, although this hasn’t translated to sales. And just last week, BlackBerry finally showed up in the game, and seems to be doing better than the week before.

Now we have four players in the mobile market, but even more mobile OSes are about to appear on the horizon.

Firefox OS is said to be due shortly; Samsung plans to sell Tizen handsets this year; and now we have reports that Ubuntu Phone is due in October.

Let’s not pretend that any other OS is going to catch iOS or Android any time soon, but if any one of Firefox, Tizen, or Ubuntu can gain a few market usage percentage points and if a couple of developers are successful enough that they can talk about how they can make a living off of the platform, then those OS ecosystems are viable. It may not be the rivers of gold that the iTunes store is painted as, but it’ll be enough.

What I find interesting is the approach that each of the OSes have taken towards developers in their application language selection — choosing the web over a mature, strongly-typed language.

Firefox will run apps built in HTML5 and use JavaScript to communicate with the hardware; Ubuntu will have its native applications built in Qt, but HTML5 apps will also have the ability to access the system’s features and be treated as a first-class application; and Tizen is also targeting developers that are familiar with a HTML5 toolkit.

This technique of targeting web developers is currently being tested in the field with BlackBerry 10, and in the next few months, we will be able to see if targeting a large developer base works and if web developers can make the change in domain to mobile a successful one.

In case you think that choosing JavaScript as a platform’s language is an idea confined only to mobile operating systems, the GNOME project announced recently that it was moving to use JavaScript as its default language for applications. The internet groupthink proclaimed that “it’s outrageous; the GNOME developers have gone mad!”— conveniently forgetting about another operating system that allows JavaScript-built applications to run, called Windows 8.

The second aspect of the approach from these new mobile OSes that I find interesting is that they are targeting emerging mobile markets.

Ubuntu says that they will target “two large geographic markets”, where ever that may be, but Ubuntu’s founder Mark Shuttleworth has said previously that it will focus on developing economies. Similarly, Firefox OS is expected to launch first in Brazil.

By focussing on markets where premium smartphones are far beyond the reach of much of the population, the new OSes have the chance to gain some precious momentum and user share before the eventual launch into the smartphone saturated regions of the developed world.

Keep in mind that the company formerly known as Research In Motion was able to keep its head barely above water while it developed BB10 because, as it was haemorrhaging users in the first world, it was picking them up in the developed world.

Riding the rise of the developing economies is an easier proposition than tackling the iPhone/Android hegemony that is present across the developed world.

The odd OS out here is Tizen, but where Ubuntu and Firefox OS are coming from a position of weakness, Tizen is arriving from a position of comparative strength. Backed by Intel and Samsung, if any new OS has a chance of cracking the iPhone/Android duopoly head-on, it is Tizen.

Some argue that it isn’t so much an iPhone/Android duopoly, but rather an iPhone/Samsung duopoly. We will find out the result of this assumption over the coming months this year when Tizen launches.

In a perfect world, I’d personally love to see each of these OSes gain somewhere between 5-10 per cent, with Windows Phone and BlackBerry having similar numbers and the rest owned by iOS and Android.

But like all perfect worlds, it does not exist, and the reality that awaits these new OSes is sure to be harsh.

Hopefully one or possibly two these OSes will be able to not only survive, but thrive.

It’s been a long time since developers have had to concern themselves with an explosion of platforms of this magnitude.

Even though these OSes will not enter the calculations of most developers, for those that do take an interest, it’s sure to be an exciting and unpredictable adventure. One that I hope will benefit all mobile users, it’s the way that computing is headed.