Do 4.3 JellyBean apps work on 4.4 KitKat? I am an android developer and would like to upgrade my Nexus 7(2013, JellyBean 4.3) to KitKat 4.4.2. 

My apps are all developed to work on 4.3 fine. I'm just wondering if my 4.3 apps will work when I upgrade. Does anyone know?

Thanks in advance.

EDIT - I upgraded and all apps work fine, thanks for answers :D

EDIT 2 - Actually, one of my Bluetooth Low Energy Apps does not work. Any Help? I have changed the targetSDK version to 19, but should I install the SDK for 19 as well?
There's no gurantee that they'll work, but API compatibility when upgrading is a standing tenet of Android. The odds are very high (above 90%) that they'll work no problem.

In the end, whether they work or not depends on you, as the developer. As an Android developer, you should probably read the documentation released with new API's for the features and methods you use.

One way or another, you may need to upgrade to 4.4 as soon as you can - in order to address potential bugs that may pop up for your users.