Is it possible to develop a keyboard app?

I've been using Lumia 1520 for the past year and while I have gotten used to not having most of my Android apps, there's only one I miss badly, and it's Swiftkey.
Microsoft keyboard probably works good if you only type in one language, but is VERY dumb for us multilingual people. I write in 3 languages on a daily basis and it's tedious having to switch between languages.
With Swiftkey I can just connect to my Facebook and let it scan all my messages, then it remembers how I type and it auto corrects and predicts words perfectly. It's hard to explain how accurate and great it is, remembering words with three completely different languages.

I prefer Windows phones though... and would not mind learning and making my own keyboard app. But I have not seen any in the store, so is it even possible?

Apparently that's almost impossible as even the Swype-like function on Windows Phones/W10 Mobiles are baked into the OS itself. 'Almost impossible' because we'll never know what Microsoft's planning for W10M in the future.

Btw, I'm no developer. My answer comes from reading through various posts such as yours in this forum.

Not possible at the time, the keyboard we have is all we have.

That's a damn shame.

Swift key for WM would be great. I like it's cursor keys better than WM Dot thingy.